SEOUL, South Korea — Two fuel trains collided and blew up at a North Korean railroad station near the Chinese border Thursday, South Korean media reported, with one television channel saying as many as 3,000 people might have been killed or injured.
The secretive communist government in Pyongyang declared an emergency while cutting off international telephone lines to prevent details of the crash from leaking out, South Korea's Yonhap news agency reported.
The North Korean leader, Kim Jong Il, had quietly passed by rail through the station as he returned from China before dawn some nine hours earlier. It was not clear what caused the crash, or if it was related to Kim's journey.
But a South Korean official, quoted on condition of anonymity by South Korea's all-news cable channel, YTN, said it appeared to be an accident.
The collision reportedly took place about 1 p.m. in Ryongchon, a town 12 miles from China. One train was carrying oil and the second had liquefied petroleum gas, media reported.
"The area around Ryongchon station has turned into ruins as if it were bombarded," Yonhap quoted witnesses as saying. "Debris from the explosion soared high into the sky and drifted to Sinuju," a North Korean town on the border with China, it said.
Cho Sung-dae, a Yonhap correspondent in Beijing, said his reports were based on residents in the Chinese border city of Dandong who talked with their relatives in Ryongchon.
They described a massive explosion involving a large number of casualties but could not give figures, Cho told The Associated Press. Cho also said North Korean authorities appeared to shut down the border with China after the incident.
Subsequent attempts by his Chinese sources to contact people in Ryongchon failed because the phone lines apparently had been severed.
YTN reported that the number killed or injured could reach 3,000. A YTN reporter in Seoul, speaking on condition of anonymity, told AP the network's casualty count came from a South Korean government official, whom he declined to identify.
A South Korean Defense Ministry official confirmed "a large explosion near Ryongchon station," Yonhap reported. "We have yet to find out the cause of the incident, the kind of explosion and how many died," the official said, speaking on condition of anonymity.
Yang Jong-hwa, a spokeswoman of South Korea's Unification Ministry, said her organization could not immediately confirm the reports; the ministry is in charge of relations with North Korea. The Defense Ministry could not comment, and the Foreign Ministry could immediately be reached.
The accident apparently resembled a disaster in Iran on Feb. 18, when runaway train cars carrying fuel and chemicals derailed, setting off explosions that destroyed five villages. At least 200 people were killed.
North Korea is one of the world's most isolated countries and rarely allows visits by outside journalists. News events within its borders are difficult to confirm independently, and the state-controlled media is unlikely to provide quick confirmation of such an accident.
The communist country's infrastructure is dilapidated and accident-prone. Its passenger cars are usually packed with people, and defectors say trains are seldom punctual and frequently break down.
Sometimes, trains are stranded for hours at stations until their electricity supply is restored enabling them to continue, some defectors say.
The trunk line on which Thursday's accident reportedly occurred, the main rail link between China and North Korea, was first laid during the Japanese occupation more than 60 years ago.
YTN reported that the casualties included Chinese living in the North Korean border region, and that Chinese in Dandong — a bustling industrial city on Yalu River — were desperate to learn about their relatives. Chinese and North Korean traders frequently cross the border at Dandong.
Some of the injured were evacuated to hospitals in Dandong, it said.
Kim rarely leaves North Korea and when he does takes a special train, reportedly armored, because he is known to have a fear of flying.
North Korea's state-run news agency on Thursday confirmed that Kim made a secretive trip to China on Monday through Wednesday, but carried no comments on the reported explosion.
China, which also confirmed Kim's visit, is North Korea's last major ally, and the countries' ruling communist parties boast of close ties. But while China's experiments with capitalism have transformed it into an economic dynamo, North Korea suffers chronic food shortages and depends on its larger neighbor for aid.
Kim met with President Hu Jintao and other Chinese leaders and agreed to "push ahead" with a peaceful resolution to the standoff over its nuclear weapons programs, the North's official KCNA news agency and central television network reported earlier Thursday.
The broadcast added that Kim said his government "will continue to be patient and flexible and actively participate in the process of six-nation talks and contribute to making progress at the talks."
The comments were likely to be encouraging to the United States and other countries, who want China to use its leverage as North Korea's leading supplier of food and energy aid to get the country to disarm.
Washington wants Pyongyang to dismantle its nuclear facilities, but North Korea has said it doesn't trust the United States not to invade and wants a security guarantee.
The last round of six-nation talks — involving China, the two Koreas, the United States, Japan and Russia — ended in February in Beijing without a settlement.