Two trains smashed head-on in the early morning darkness Monday, flipping cars on top of one another and hurling sleeping passengers though flaming compartments in one of India's deadliest rail accidents.

The government said today that 223 people were killed and about 300 injured, but rescuers had not reached all 15 cars involved. Railway officials said the death toll was likely to climb to 250, and news agencies said it could exceed 400. Many passengers remained trapped in the mangled cars early today, rescue officials said.

Some 2,500 passengers were on the two trains. Many were soldiers or paramilitary troops traveling to or from Assam, a remote state in northeastern India wracked by separatist insurgency and tribal warfare.

The collision at Gaisal, a remote station near the border with Bangladesh, left some train cars pointing vertically and others crumpled like paper. Bodies covered with white shrouds were lined up beside the tracks.

A fire engulfed several coaches, burning some passengers to death, officials at railway headquarters in Guwahati said.

Medical workers were visibly shaken while working amid the grisly wreckage, where limbs hung limply from a tangled mass of steel. "We are used to seeing dead bodies daily, but I've never seen anything like this," C.P. Singh, a physician, said on STAR television.

Train accidents in India are common, and railway officials acknowledge that 60 percent of India's 400 train accidents a year are caused by human error. The country has the world's largest railway network under one management, with more than 14,000 trains carrying 12 million people daily.

India's deadliest train accident took place in 1981, when more than 800 people were killed when a train plunged into a flood-swollen river in the eastern state of Bihar.

The Brahmaputra Mail train from Guwahati and the Awadh-Assam Express from New Delhi slammed into each other just before 2 a.m. Monday in Gaisal station, a small-town rail stop in West Bengal state, midway between Calcutta and Guwahati.

The station had two separate tracks, and officials said a signal error may have put the trains on the same one.

Initial reports of the disaster spoke of an explosion, and one report by the BBC said one train was carrying military explosives. Railway officials said they had no knowledge of explosives aboard either train.

A survivor, Prabir Dey, said most of the passengers on his train were asleep when the express slammed into it.

"Suddenly we heard a huge crack. One carriage climbed right over our compartment," said Dey, a businessman. He lost consciousness after the impact and woke up in an ill-equipped hospital in the nearby town of Islampur, where he was given first aid. His business associate was killed.

Still dazed and barely able to speak because of his injuries, Dey caught a bus for the 14-hour ride to Calcutta for further treatment. His clothes were stained with dried blood and his hand was broken.

All four of the engineers on the trains died, the government said.

Prime Minister Atal Bihari Vajpayee called the collision "a great tragedy" and ordered an official inquiry. President K.R. Narayanan said the crash "highlights the crying need to improve rail safety measures."