DANDONG, China -- Aid workers allowed Saturday into secretive North Korea described a ring of devastation around this week's massive train explosion and said 76 of the 154 people confirmed dead were children in a school destroyed by the blast.
In an unusually frank statement, North Korea blamed the blast in Ryongchon on human error, saying the cargo of oil and chemicals ignited when workers knocked the wagons against power lines.
"There was just rubble everywhere and very large craters in the ground. The buildings around were totally flattened, especially the houses," Red Cross official Jay Matta said by telephone from a nearby town. "It's just a mess everywhere."
North Korean officials said the explosion at a railway station killed at least 154 people and injured 1,300, Matta said. Half of the dead were children, killed when their school was destroyed.
John Sparrow, a Red Cross spokesman in Beijing, said 76 children died. He said 129 public buildings were destroyed and 120 damaged, including a hospital and agricultural college.
"The railroad station and the immediate surroundings were obliterated," Sparrow said.
Huge radius of damage
The aid workers' visit followed a rare invitation from the North's communist government, which relaxed its normally intense secrecy as it pleaded for international help.
The explosion destroyed buildings in a radius of hundreds of yards, ripped the roofs off others and broke windows up to 2 1/2 miles out, aid officials said. They said local officials estimated Ryongchon's population at 27,000, though some estimates put the number much higher.
North Korea, in its first statement on the disaster, said in a dispatch by its state news agency that the explosion was touched off by "electrical contact caused by carelessness during the shunting of wagons loaded with ammonium nitrate fertilizer." Ammonium nitrate can be extremely volatile.
Separately, China's state news agency cited a North Korean official saying trains carrying oil and the chemical fertilizer collided and were ignited by a downed power line.
The foreign aid workers saw no signs of any dead or wounded North Koreans, Matta said. "It looks like they did a thorough search before we came," he said.
"The impression from what we saw was that the initial rescue operation was completed," said Dr. Eigil Sorensen, the World Health Organization representative in Pyongyang.
A three-story agricultural school near the station "was totally leveled," Sorensen said. At a three-story primary school about 300 yards from the station, the roof was ripped away and the top floor collapsed, he said.
North Korean officials said about 350 injured people were hospitalized in Sinuiju, a bigger city on the Chinese border, according to Sorensen.
Aid workers didn't go there Saturday because Sinuiju is a special economic zone and North Korean officials hadn't prepared the required entry permits, Sorensen said. But he said they were promised access within the next two to three days.
Aid workers said they saw people pulling furniture and other belongings from wrecked homes.
"We could see people on ox carts carrying their belongings ... to relocate within the town to the homes of friends and neighbors," Sorensen said.
He said he believed it was unlikely that a large number of people were buried under the rubble, and that North Korean officials said five people were unaccounted for.
The aid workers delivered surgical materials, disinfectant and medicines. Matta said the North Korean Red Cross requested tents, cooking equipment and water purification tablets.
Lee Yoon-gu, president of South Korea's Red Cross who returned home Saturday after a five-day visit to Pyongyang, said about 2,000 houses at Ryongchon are believed to have been completely flattened or damaged.
He said he had proposed sending doctors to help, but had not received any response from the North even though his Northern counterpart had asked for assistance.
Chinese villagers 12 miles away said they were shaken by the force of the blast and saw a black, mushroom-shaped cloud tower over the horizon.
The North's news agency KCNA said "the damage is very serious" and expressed appreciation for promises of international humanitarian assistance.
North Korea restricts the movement of foreigners, and groups that distribute aid to alleviate its food shortages are barred from some areas.
Aid workers have been allowed to visit areas struck by drought or floods in recent years, but the government has never arranged such quick access to the scene of a disaster like the train explosion. Those visiting the site Saturday were not allowed to carry mobile communications.
China has also offered assistance. State Department spokesman Richard Boucher said Washington was evaluating the situation to see "if there is a need or an opportunity for the United States to help."
There was no sign in Dandong, a Chinese border city about 12 miles from Ryongchon, of injured North Koreans. The city's three biggest hospitals had prepared for a possible surge of patients.