People pulled concrete off bleeding victims and passengers kicked out windows and crawled to safety amid crying and screaming after the arriving New Jersey Transit train ran off the end of its track.
It apparently knocked out pillars as it ground to a halt in the covered waiting area, collapsing a section of the roof onto the first car.
"All of a sudden, there was an abrupt stop and a big jolt that threw people out of their seats. The lights went out, and we heard a loud crashing noise - like an explosion - that turned out to be the roof of the terminal," said Ross Bauer, who was sitting in the third or fourth car when the train was pulling into the historic 109-year-old station for its final stop.
"We're panicking, because I believe those people in the front were very badly injured," a passenger, Jamie, told reporters at the scene. "So they started yelling, because they saw the blood."
WATCH: Train passenger describes chaos at the scene
Gov. Chris Christie said a woman standing on the platform was killed by debris. A total of 108 others were injured, mostly on the train, Christie said; 74 were hospitalized.
The woman who died was later identified by the state medical examiner's office as 34-year-old Fabiola Bittar de Kroon of Hoboken.
Of the injured, two people are said to have critical/life-threatening injuries, while the rest suffered non life-threatening or minor injuries. According to a federal official at the scene, the train engineer was among those hospitalized.
"The train came in at much too high rate of speed, and the question is: 'Why is that?'" Christie said. New York Gov. Andrew Cuomo said investigators will determine whether the explanation was an equipment failure, an incapacitated engineer, or something else.
The cause of the crash wasn't immediately known. The National Transportation Safety Board sent investigators. The agency will want to know what the operator was doing before the crash and whether the person was distracted, said Bob Chipkevich, who formerly headed the NTSB train crash investigations section.
MORE: Passengers describe harrowing scene at NJ Transit crash
"I heard a kaboom, and the whole place shook," said William Blaine, an engineer for a freight line who had just gotten off a train. "Everybody got quiet, because the first thing you think is a bomb...I ran out, and I just saw people all over the ground and debris all over the place."
None of NJ Transit's trains are fully equipped with positive train control, a safety system designed to prevent accidents by automatically slowing or stopping trains that are going too fast.
The industry is under government orders to install PTC, but the deadline has been repeatedly extended by regulators at the request of the railroads. The deadline is now the end of 2018.
"While we are just beginning to learn the cause of this crash, it appears that once again an accident was not prevented because the trains our commuters were riding lacked positive train control," said Rep. Sean Patrick Maloney, D-N.Y. "The longer we fail to prioritize investing in rail safety technology, the more innocent lives we put in jeopardy."
But both Cuomo and Christie said that it is too soon to say whether such technology would have made a difference in this crash.
The train left Spring Valley at 7:23 a.m. and was apparently running late. Witnesses said the train was moving fast when it slammed into the platform. Passengers told WABC-TV that there was absolutely no braking as the train pulled into the station.
"I stepped over a body, and it was dead woman," Blaine said. "I backed up, and people started running over, and I just started telling people they needed to get back, because there was electrical wiring and water running, and the ceiling was about to cave in."
PHOTOS: Train crash in Hoboken
Officials said most of the injured appear to be in the first car or are people who were struck by debris inside the station. Passengers on the second car and behind were able to exit the train.
Hoboken, which is NJ Transit's fifth-busiest station with 15,000 boardings per weekday, is situated just across the Hudson River from New York City. It is the final stop for several train lines and a transfer point for many commuters on their way to New York City. Many passengers get off at Hoboken and take ferries or a PATH commuter train to New York.
NJ Transit provides more than 200 million passenger trips annually on bus, rail and light rail lines. More than 100,000 people use NJ Transit trains to commute from New Jersey into New York City daily.
A crash at the same station on a different train line injured more than 30 people in 2011. The PATH commuter train crashed into bumpers at the end of the tracks on a Sunday morning.
WABC-TV, ABC News and Associated Press contributed to this report.