Metro-North Tragedy: How the Most Fatal Train Crash in Its History Unfolded

— -- The fatal train crash in suburban New York unfolded in the middle of the evening rush hour as hundreds of people were headed home.

The Metro-North crash, which left six people dead and more than a dozen others were hospitalized with injuries, is under investigation -- but a timeline of the accident has started to emerge.

Here is what happened:

5:44 p.m. Tuesday, Feb. 3

A Metro-North Railroad train departs from Grand Central Station on the Harlem line, which cuts through the center of Westchester County.

About 700 passengers were believed to be on board.

6:33 p.m.

The crash occurred about 45 minutes into the journey, near the town of Valhalla, New York, which is 20 miles north of New York City.

The Metropolitan Transportation Authority confirmed the time of the crash as 6:33 p.m.

The crash came when the train slammed into a Jeep SUV that was on the tracks at the Commerce Street grade crossing.

The circumstances of the collision remain under investigation.

The SUV wrapped around the front of the train and was driven 400 feet down the track, dislodging the electrified third rail. The rail went through the SUV, punctured the gas tank causing an explosion, and then came through the floor of the train behind the motorman’s compartment.

"You had a metal rail going right down the train like a ramrod," Gov. Andrew Cuomo told ABC News Radio this morning. "That’s what caused massive destruction.

"This was as ugly as anything I have ever seen," he said.

Passengers began evacuating the train, and the worst of the destruction appeared limited to the first train car.

"I saw flames coming at me, about a foot from my head," passenger Christopher Gross told ABC News this morning.

6:44 p.m.

Dr. Ivan Miller, the director of Westchester Medical Center, said at a news conference Wednesday that the hospital received the call 11 minutes after the crash and declared it a mass-casualty incident three minutes later, at 6:47 p.m. The declaration allowed the hospital to begin a protocol to prepare for a large number of trauma patients.

7:13 p.m.

Metro-North announced via Twitter that it was suspending all train service between North White Plains and Pleasantville, New York, as a result of the accident.

Three hours later, it announced that all northbound Harlem line trains out of Grand Central would stop at North White Plains.

7:20 p.m.

The first of 12 patients were brought to Westchester Medical Center for treatment, including five patients who were considered 'stage one' priorities given the extent of their injuries, Miller said.

"Initial word was that we might be receiving a lot more, so we were preparing to receive a lot more," Miller said.

10:12 p.m.

The National Transportation Safety Board announced that it would be sending a go-team of investigators from its Washington, D.C., headquarters to New York to survey the scene.

This Morning

MTA officials confirmed to ABC News that the driver of the train was expected to survive after being held overnight in the hospital.

Officials revised the number of announced fatalities down from seven to six -- five train passengers and the driver of the SUV, most of them said to be burned beyond recognition. There were 15 other passengers who are being treated for injuries.

Victims' families were meeting at the medical examiner's office this morning to attempt to make the final identifications.

11:00 a.m.

The head of the NTSB go-team held a news conference shortly after arriving on the scene but did not release any new information because it had not yet been able to confirm any information about the crash.

1:00 p.m.

Miller said that four of the patients who had been transported to Westchester Medical Center immediately after the accident were released from the hospital overnight and eight remained.

Chief nurse executive Patricia Wrobbel said that of the eight, one patient remained in critical condition, one in serious condition, four in fair condition and two in good condition.