NEW YORK, DEC. 28 -- A routine subway commute from Brooklyn into Manhattan became a nightmare this morning as fire broke out in a subway tunnel and smoke filled several trains. One person died, and at least 145 were reported injured.

New Yorkers have been warned recently that the city's transportation infrastructure is in a dangerous state of deterioration, but authorities blamed today's accident on the heavy snowfall that blanketed the city last night.

Joseph Gaynor, a supervisor with the state's Public Transportation Safety Board, said preliminary investigation showed that snow had dripped onto a conduit cable connected to the electrified third rail, causing a short circuit and at least one explosion.

Authorities said it was not immediately clear how snow reached the cable because there are no gratings or surface openings at the site. Transit Authority spokesman Termaine Garden said snow may have piled up on the train, which also runs above ground.

Asked why such explosions do not occur every time there is snow or rain, Gaynor said, "There could be other factors involved, and we will continue to investigate."

Other than suicides and passengers killed while trying to walk between cars, fatalities attributed to malfunctions in the subway system are relatively rare, Garden said. The last death in a subway fire occurred more than 20 years ago, he said.

The fire broke out at 9:12 a.m. on the IRT no. 2 and 3 line just south of the Clark Street station in Brooklyn, sending smoke streaming into the tunnel in both directions -- toward Borough Hall station in downtown Brooklyn and under the East River toward Manhattan, said Transit Authority spokeswoman Caren Gardner.

Subway passengers said flames licked at the windows and thick black smoke filled the train, causing some people to pass out while others vomited. It was unclear whether the tunnel's exhaust-fan system was operative.

"We really thought we were gone, that we wouldn't see New Year's," said Gertrude Hoyte, 51, a Brooklyn resident on her way to work in Manhattan. She and several other witnesses spoke with the Associated Press.

Naomi Smalls-Watson, 23, of Brooklyn said she "heard a popping noise and then a whoosh . . . then there was another big boom, and people started panicking." She said smoke in the tunnel was so dense that people could not see anything outside the train.

Dana Sullivan, 28, of West Islip, N.Y., said that "people were screaming, 'We're going to die,' " and that others were praying aloud.

Three trains affected by the fire were backed up to Borough Hall station, where passengers were evacuated, Gardner said. Stunned commuters sat in the lobbies of a nearby bank and courthouse, where employees brought them water and paper towels.

On the slushy sidewalks outside the subway station, people lined up to be examined by Emergency Medical Service (EMS) workers. EMS spokeswoman Sandra Sharpe said that 145 people were treated on the scene and that 132 of them were sent to nearby hospitals.

"Of those taken to hospitals, the majority were suffering from smoke inhalation, although there were all types of injuries," Sharpe said. "One female was taken to the hospital in cardiac arrest."

That unidentified woman, 37, and one man in full cardiac arrest who died were taken to Long Island College Hospital, where the woman was reported in critical condition, a hospital spokesman said. The man was identified as Peter Hagen, 35, of Smithtown, N.Y., transit police said.

The accident followed a week of dire warnings about the perilous state of New York's bridges and subways. On Thursday, transportation officials closed the N subway line across the Manhattan Bridge after state inspectors found that the beams supporting the track were badly corroded. City engineers have warned that dozens of the city's 842 bridges will need repairs in the next year.