Netanyahu's visit to China's eastern financial hub on Tuesday followed Israel's weekend airstrike on a Syrian military complex near Damascus. That killed at least 42 Syrian soldiers and destroyed an Iranian shipment of guided missiles destined for Israel's sworn foe Hezbollah in Lebanon.

The prime minister hasn't directly commented on the raids during his China trip, which is largely focused on strengthening economic ties. On Tuesday, Netanyahu and his wife toured Shanghai's Ohel Moshe synagogue in the Hongkou district that was home to many of the 18,000 Jews granted refuge in Shanghai from the horrors of Nazi persecution.

Netanyahu said that "while the fate of the Jewish people has changed significantly since then, when Jews could only plead to be rescued, today the Jewish people has a state and army of its own, and no longer needs to plead to be rescued," according to a statement from his office.

Hongkou is also home to the Shanghai Jewish Refugees Museum and a considerable amount of prewar housing that has survived destruction during the city's recent rise as a regional financial powerhouse.

Netanyahu is to arrive in Beijing on Wednesday for talks with Premier Li Keqiang and President Xi Jinping, just one day after the departure of Palestinian President Mahmoud Abbas. China's hosting of the two during the same week emphasizes its desire for a bigger role in the Middle East.

The Israeli attacks on Syria have underscored the difficulty of China's quest to retain a balance in its relations with the regional players. For a second day, Chinese Foreign Ministry spokeswoman Hua Chunying expressed China's opposition to such interventions, without mentioning Israel by name.

"We call on all sides of Syria to give top priority to the interest of the Syrian people, launch political dialogue and carry out the political transition as soon as possible," Hua said, in answer to questions at a regularly scheduled news conference.

"China also calls on all sides concerned to earnestly respect Syria's sovereignty and territorial integrity, remain restrained and calm, avoid the use of military force and acts that might raise tension, and play a responsible and constructive role in politically resolving the Syrian issue," she said.

While in Shanghai, Netanyahu also visited an industrial park and met with Mayor Yang Xiong, with whom he agreed to establish joint research agencies to develop technologies in water use, renewable energy, and public health.

Officials at the Citizen Safety Department of Mexico State, which surrounds the capital, did not rule out the possibility the death toll could rise. At least a dozen people remained hospitalized late Tuesday, several of them in critical condition.

Gov. Eruviel Avila said late Tuesday that 22 people were known dead in a letter to Pope Francis, with whom he was supposed to meet at the Vatican on Wednesday. Avila said he was returning to Mexico instead.

The state safety department's spokesman, Cesar Diaz, said emergency workers would continue searching through the night in the charred remains of vehicles and homes built near the highway on the northern edge of the metropolis.

Residents pitched in to rescue people from the wreckage of the 5:30 a.m. explosion, crushed and burned cars and shattered homes. Television footage showed plumes of flame shooting out of homes in the pre-dawn darkness.

A huge piece of the truck's gas tank was blown 50 yards by the blast, landing atop the wall of a house and cars parked outside.A number of pigs, goats and other farm animals that were kept on patios were killed.

"It was thunderous sound. I thought we were all going to die," said Rita Enriquez, 42, a housewife who lives nearby. "When we ran out, we saw a car on fire and flames everywhere. Smoke was pouring all over the freeway."

Mario Lopez, 43, a mechanic, lives in the house hit by the tank and managed to escape with his three sons after being awakened by the blast.

"All the windows broke to the inside. We got down and left crawling," said Lopez, who lost a brother, a sister, three nephews and a sister-in-law who all lived in separate units of the three-story home. He said 12 people in all died in the house."Everything was in flames," he said.

Enriquez said five of her relatives were gravely injured in their concrete slab home along the road, though she had no other details as she waited for word outside Magdalena Las Salinas Hospital in Mexico City.

Her 15-year-old niece, Wendy Garrido, who was pregnant, was forced to give birth after the explosion, she said. They survived but both were in intensive care, Health Secretary Cesar Gomez said.

The pre-dawn disaster exposed two recurrent public safety issues in Mexico: extremely heavy trucks that are frequently involved in serious accidents, and the construction of improvised homes just feet away from major highways.

Some of the cinderblock homes hit by the huge explosion were just steps from the busy, eight-lane highway. Other homes were mere shacks, built of sheet tin.

Lopez said the highway recently had been widened, bringing traffic perilously closer to their dwellings.

"They never thought a car could hit them or an explosion of this magnitude," said Maribel Juarez, the cousin of another family killed in the explosion. "Now we have to bury their coffins and our family members are never going to return."

The driver, Juan Olivares, 36, was heading south from the city of Pachuca to Mexico City in a tractor that was hauling two gas tanks on tandem trailers, said Jose Luis Cervantes, an assistant state prosecutor. He said the vehicle belonged to the Termogas company.

Cervantes said the tractor hit a center divider and broke apart, with one tank flying into a house and exploding, killing 15 people, and another part of a tank hitting a separate house, killing four.

State security officials counted 33 people with various injuries.

The driver, who was under detention while being treated at a hospital, could face manslaughter and property damage charges, the prosecutor said.

"We just pulled burned people, and put out the fire in the houses, but we don't really know what happened," said Rogelio Martinez, a resident.

Emergency personnel at the scene pulled dead from their homes, some apparently burned in their beds. An Associated Press journalist saw rescue workers carry three bodies, covered with white sheets, from one home.

One small passenger van had been totally gutted by flames and tossed against the wall of one of the many improvised houses next to the highway.

Hundreds of police, ambulance drivers, paramedics, soldiers and firefighters gathered at the scene.

Pablo Bedolla, the mayor of Ecatepec, a mainly working-class area, said 20 homes and one school had been damaged by the blast. The explosion happened before class hours, so there were no apparent injuries in the school.

"People are very shaken, above all because of the injuries and the large number of dead," Bedolla said. "I've spoken with the families of the victims, and they are just sobbing."

The explosion closed the highway between Mexico City and Pachuca for hours.

Speaking in Mexico City, President Enrique Pena Nieto suggested something would have to be done to separate major highways from poor neighborhoods.

"I have instructed the Transportation Department ... to review the safety conditions on this federal highway in places where structures have been built on the right of way, so that in the near future, work can be carried out to make it safer," Pena Nieto said.

Often in Mexico, squatters settle on rights of way, the strips of land on either side of a highway or railway line that are intended to be buffer zones. The gradual spread of shacks creates neighborhoods that are inherently unsafe.

This highway, however, was recently expanded, so it was unclear whether the land occupied by homes was legally settled.

The Mexican government also appears to have realized it has a big problem with over-weight trucks. Such trucks, often unsafely operated, have been involved in a number of spectacular, deadly accidents in recent years.

On Tuesday, the Transportation Department announced it had set up a panel of experts to study the issue of maximum allowable weights, "to set out opinions on eventually changing the weight standards, or drawing up a new set of rules."

One year ago, the Mexican government announced measures to tighten inspections and lower maximum allowed weights for some freight trucks after protests over a string of deadly accidents involving double-trailer trucks like the one involved in Tuesday' disaster.

Mexico has allowed trucks to travel highways with loads of up to 80 metric tons and lengths exceeding 100 feet, compared to a U.S. limit of 80,000 pounds, or 40 tons, on interstate highways.

In April 2012, a double-trailer truck on a two-lane road in the Gulf coast state of Veracruz lost its rear trailer, which slammed into a bus carrying farm workers, killing 43 people.

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Associated Press writers Mark Stevenson and Gloria Perez contributed to this report.

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AP video: http://www.youtube.com/watch?v=jXv190oaFVw

The Netherlands National Prosecution Office said a 35-year-old suspect it identified only by his initials, S.K., was arrested Thursday at his home in Barcelona. Authorities also seized computers and mobile phones. Dutch prosecutors do not release full names of suspects, in line with privacy laws.

According to a prosecution statement, the man is suspected of "unprecedentedly serious attacks on the non-profit organization Spamhaus." He was held on a European arrest warrant and is expected to be extradited to the Netherlands to face justice.

The so-called denial-of-service attack on Spamhaus fired a torrent of data at the organization's servers and was blamed for other disruptions online. Dutch banks and an electronic payment service also have been hit by similar attacks in recent weeks, but prosecutors say they do not believe they are linked to the Spamhaus incident

Spamhaus, a site responsible for keeping ads for counterfeit Viagra and bogus weight-loss pills out of the world's inboxes, said it apparently was targeted by groups angry at being blacklisted by the Swiss-British group.

Prosecutors said the cyberattack also hit "partners" of Spamhaus in the United States, the Netherlands and Britain.

At the time, Vincent Hanna, a researcher with Spamhaus, called it a "small miracle" the organization had remained online during the cyber onslaught.

Denial-of-service attacks overwhelm a server with traffic like hundreds of letters being jammed through a mail slot at the same time. Security experts measure those attacks in bits of data per second. Recent cyberattacks such as the ones that caused persistent outages at U.S. banking sites late last year have tended to peak at 100 billion bits per second.

But the assault on Spamhaus shattered the charts, clocking in at 300 billion bits per second, according to San Francisco-based CloudFlare Inc., which Spamhaus enlisted to help it weather the attack.

Now, in a study published in the journal , scientists say that changes in the population of bacteria living on and around the penis may be partly responsible.

Relying on the latest technology that make sequencing the genes of organisms faster and more accessible, Lance Price of the Translational Genomics Research institute (TGen) and his colleagues conducted a detailed genetic analysis of the microbial inhabitants of the penis among a group of Ugandan men who provided samples before circumcision and again a year later.

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While the men showed similar communities of microbes before the operation, 12 months later, the circumcised men harbored dramatically fewer bacteria that survive in low oxygen conditions. They also had 81% less bacteria overall compared to the uncircumcised men, and that could have a dramatic effect on the mens ability to fight off infections like HIV, says Price. Previousshowed that circumcised men lowered their risk of transmitting HIV by as much as 50%, making the operation an important tool in preventing infection with the virus. Why? A high burden of bacteria could disrupt the ability of specialized immune cells known as Langerhans cells to activate immune defenses. Normally, Langerhans are responsible for grabbing invading microbes like bacteria or viruses and presenting them to immune cells for training, to prime the body to recognize and react against the pathogens. But when the bacterial load increases, as it does in the uncircumcised penile environment, inflammatory reactions increase and these cells actually start to infect healthy cells with the offending microbe rather than merely present them.

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That may be why uncircumcised men are more likely to transmit HIV than men without the foreskin, says Price, since the Langerhans cells could be feeding HIV directly to healthy cells. His group is also investigating how changes in the levels of cytokines, which are the signaling molecules that immune cells use to communicate with each other, might be influenced by bacterial populations.

There is a real revolution going on in our understanding of the microbiome, says Price, who is also professor of occupational and environmental health at George Washington University. The microbiome is almost like another organ system, and we are just scratching the surface of understanding the interplay between the microbiome and the immune system.

Previous work suggested that changes in the bacterial populations in the gut, for example, could affect , and other studies found potential connections between microbial communities and the risk for cancer, asthma and other chronic conditions.

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Crowder's First Baptist Church in West remains blocked off as investigators work on the scene of Wednesday's blast that killed at least 14 people and injured 200. So about 100 people sat in white folding chairs Sunday morning, while others carried their own.

"We have lost our friends and neighbors," Crowder told the audience. We have lost the safety and comfort of our homes. But as scary as this is, we don't have to be afraid."

Authorities have not yet identified what caused the blast, which was so powerful it registered as a small earthquake. Assistant state fire marshal Kelly Kistner said the blast left "a large crater."

The explosion destroyed about 50 homes and severely damaged a nursing home and other buildings nearby. Kistner said all fires have been extinguished at the explosion scene and the remaining fertilizer tanks at West Fertilizer Co. are not a danger.

Some of the people who attended Sunday's outdoor service wore T-shirts calling on others to "pray for West."

"Every time I close my eyes, all I can think about is the explosion," said Edi Botello, a senior at West High School. "People running around. People evacuating. There was one point I couldn't even talk. I just stuttered."

The destruction was evident in a short visit to the area organized for reporters.

An apartment building just across the railroad tracks from the plant appeared to bear the brunt of the explosion, according to a pool report. The building's roof was collapsed, its windows were blown out and chunks of concrete from the plant littered the space between the tracks and the apartments.

"Several blocks we had projectiles or shrapnel that has been found of different sizes," Kistner said. "Smaller pieces have been found blocks away."

The wave radiating from the blast also hit the nursing home across the street from the apartments. There too, windows were blown out, ceiling tiles were visible throughout the rooms and the red brick exterior was cracked. At West Intermediate School, a northern wall was charred and the southern wall showed structural damage.

Crews from Union Pacific were repairing the railroad tracks, but reporters were kept from climbing the berm to see what was happening at the fertilizer plant. Above the berm, four heavily damaged metal structures were visible at the plant.

More than 60 people are working in the blast zone for the federal Bureau of Alcohol, Tobacco, Firearms and Explosives and the state fire marshal's office.

Kristner said officials have found the seat, or center, of the explosion, "which is important, because as we conduct our investigation we'll be working from an outer perimeter inward, from the least damaged to the greatest damage. So knowing the seat of that explosion is important."

Robert Champion, the special agent in charge for ATF's Dallas office, said experts plan to get into the crater in the next couple of days and start digging it out "to see what transpired to cause this devastation."

"It's a slow process, but we're getting there," Champion said.

The town of 2,800 people was previously known in Texas for its deep Czech heritage from the designs of storefronts in the town center and the names of streets and businesses to the "Czech Stop" bakery selling kolaches and other pastries to drivers exiting Interstate 35.

At the largest Roman Catholic church in town, the Rev. Boniface Onjefu's congregation on Sunday included firefighters and emergency workers who could be spotted in bright yellow jackets.

The explosion reportedly killed 10 first responders, many of them volunteer firefighters who came after initial reports of a fire at the plant. A memorial service for first responders is scheduled for Thursday on the campus of Baylor University in nearby Waco.

"I stopped at the nursing home," Onjefu said. "I noticed a lot of people trapped. I assisted. I prayed with some and held the hands of some that needed comfort. I saw him in the eyes of everyone."

"God heard our prayers and prevented another tank from exploding."