BEICHUAN, MAY 16: A strong aftershock sparked landslides on Friday near the epicenter of this week’s powerful earthquake, while some survivors were pulled from rubble after being buried for four days.

The first foreign rescue workers since Monday’s magnitude 7.9 temblor were allowed to the scene, and helicopters dropped leaflets urging people to “unite together” and providing survival tips. For the first time, China has allowed in rescue teams from other countries, and in fact gone out of the way to seek help from Japan and Taiwan.

An aftershock rattled parts of central Sichuan province on Friday afternoon, the official Xinhua News Agency said, citing its reporters at the scene. A number of vehicles were buried on a road leading to the epicenter, and casualties were unknown.

The US Geological Survey said the latest tremor measured magnitude 5.5, one of the strongest among dozens that have shaken the area.

Education and housing officials, meanwhile, took the rare move of fielding questions online from angry Chinese citizens over the many children who died in the quake. The official death toll had risen to about 22,069 on Friday, and another 14,000 still were buried in Sichuan.

The government said it would investigate why so many school buildings collapsed in the quake — destroying about 6,900 classrooms, not including the hardest-hit counties — and severely punish anyone responsible for shoddy construction.

More than 4 million apartments and homes had been damaged or destroyed in Sichuan province, according to Housing Minister Jiang Weixin, and officials have said they expect the earthquake eventually will claim more than 50,000 lives.

Jiang said the water supply situation was “extremely serious” in Sichuan, and not flowing at all in 20 cities and counties.

A day past what experts call the critical three-day window for finding buried survivors alive, rescuers pulled a nurse to safety who had been trapped for 96 hours in the debris of a clinic in Beichuan county, one of 17 people saved there, Xinhua reported.

Survivors also were being found elsewhere, with a man pulled from the wreckage of a fertilizer plant near Shifang city.

Closer to the epicenter in the town of Yingxiu, helicopters dropped leaflets urging people to “unite together” and providing survival tips. Power and water remained cut off, forcing dazed, exhausted locals to hike 40 yards up a steep hill to a spring to fetch water.

On another hillside, at least 80 corpses in plastic body bags were placed into a trench dug by soldiers.

Dozens of people trudged up the winding mountain road to Beichuan, carrying backpacks and bags with food and medical supplies, on a quest for missing relatives.

Liu Jingyong, a 43-year-old migrant worker searching for his cousin, traveled two days by bus and now foot just to get near his relative’s home.

“I have not had any information from him,” Liu said. “This is so hard on me.”

One villager, Pan Guihui, stood on the side of the road with a vacant look on her face.

She and her husband had just hiked 13 hours with her 1-year-old child, father and two brothers away from their destroyed village further up the mountain. They had stayed in the rubble until rescue workers arrived and ordered them out because of fears of landslides.

“I have just been so frightened this whole time. I don’t know what we are going to do,” said Pan, 35. The only belongings the family had were some clothes and a little food, among hundreds camped along the road.

As she spoke, hundreds of soldiers marched by in long columns out of Beichuan, some carrying shovels.