LONDON, NOV. 18 -- At least 30 people died and scores were injured when a fire broke out tonight at central London's busiest subway and train station.

A police official on the scene at King's Cross Station described the fire as a "major catastrophe."

A number of people were said to be trapped underground several hours after the fire, which began just before 8 p.m. at the end of evening rush hour, had been extinguished. Firefighters were said to be making their way slowly through the smoke-filled underground passageways looking for other dead and injured.

{During the night, news agency reports, quoting various fire and police authorities, put the death toll at between 30 and 34. According to United Press International, police said about 100 persons were injured, 11 seriously.}

Survivors spoke of panic in the station passageways, and of seeing people with their clothing and bodies burned.

{Paul Medland, who escaped uninjured, said hundreds of passengers fought their way in a stampede to escape the smoke, UPI reported. "It was chaos," Medland said. "People were panicking and just running everywhere and treading on each other. It was awful."

{"We saw a man and a woman coming up," said a passer-by. "The man had all his hair burned off and his face was black and the woman was screaming."}

The death toll was the worst for the London subway system since Feb. 28, 1975, when a train hit a wall at Moorgate station, killing 43.

Much of central London was brought to a standstill as police blocked major roads around the King's Cross-St. Pancras station complex to allow firefighters and fleets of ambulances to reach the scene.

According to Keith Bright, chairman of London Regional Transport, the fire began in a machine room under the station's main escalator.

The fire quickly spread upward to the ticket office at the station entrance, while the heavy smoke poured down into the tunnels.

Bright said that, in addition to the smoke, the principal cause of death and injury appeared to have been the intense heat of the blaze.

Police would not speculate as to the cause of the fire, but the first indications were that it began accidentally in the escalator mechanism.

There was some speculation, tentatively rejected by Bright, that the age of the escalator involved -- one of the original wooden models installed when the underground system was opened around the turn of the century -- had contributed to the intensity of the blaze.

London Regional Transport is gradually replacing the old wooden escalators with metal models.

"I've spoken to our own experts," Bright said, "and they can't explain it at all."

Hundreds, and possibly thousands, of commuters were in the massive underground labyrinth of the station when the fire broke out. King's Cross is a junction for five subway lines, and the main London rail station for travel to the northeastern part of the country. Hundreds were taken to hospitals around the city suffering from burns and smoke inhalation.