A commuter train slammed into a sport utility vehicle stuck on the tracks at a crossing Tuesday evening, killing 6 people, mostly on the train, and injuring at least a dozen others, authorities said.

The northbound Metro-North Railroad train struck a Jeep Cherokee at a crossing in Valhalla, about 20 miles (32 kilometers) north of New York City, railroad spokesman Aaron Donovan said. Killed were the SUV's driver and five people aboard the train, he said, making this crash the railroad's deadliest.

The railroad crossing gates had come down on top of the SUV, which was stopped on the tracks, the spokesman said. The driver got out to look at the rear of the vehicle, then she got back in and drove forward and was struck, he said.

The train shoved the SUV about 10 train car lengths, and the SUV and the front of the train caught fire, he said. Smoke poured out of the scorched front rail car, its windows blackened.

Passengers described a bump and said they smelled gasoline from the vehicle.

More than 750 passengers likely were aboard the train, including Justin Kaback,commuting home to Danbury, Connecticut.

"I was trapped. You know there was people in front of me and behind me, and I was trapped in the middle of a car and it was getting very hot," he told ABC News. "All the air was turned off so there was no circulation so it was definitely scary especially when people are walking by on the outside and they said, 'The train's on fire. There's a fire.'"

Passenger Stacey Eisner, who was at the rear of the train, told NBC News that she felt the train "jerk" and then a conductor walked through the train explaining what had happened. She said her train car was evacuated about 10 minutes later using ladders to get people out.

The other rail passengers were moved to the rear of the train, which had left Grand Central Terminal in Manhattan about 45 minutes earlier.

Passengers got off from the rear. About 400 of them were taken to a local rock climbing gym for shelter. Buses were sent there to pick them up and take them to their destinations.

Metro-North is the nation's second-busiest railroad, after the Long Island Rail Road. It was formed in 1983 and serves about 280,000 riders a day in New York and Connecticut. Service on a portion of its Harlem Line was suspended after the crash.

Metro-North has been criticized severely for accidents over the last couple of years. Late last year, the National Transportation Safety Board issued rulings on five accidents that occurred in New York and Connecticut in 2013 and 2014, repeatedly finding fault with the railroad while also noting that conditions have improved.

Among the accidents was a Dec. 1, 2013, derailment that killed four people, the railroad's first passenger fatalities, in the Bronx. The NTSB said the engineer had fallen asleep at the controls because he had a severe, undiagnosed case of sleep apnea.

Last March, the Federal Railroad Administration issued a stinging report on Metro-North, saying the railroad let safety concerns slip while pushing to keep trains on time. Railroad executives pledged to make safety their top priority.