Federal investigators are looking to determine how fast a New Jersey commuter train was traveling when it crashed into a busy station Thursday morning, killing a young mother and injuring 108 others.

The National Transportation Safety Board will seek to answer the many questions surround the wreck at the Hoboken station, including whether a system designed to prevent accidents by overriding the engineer and automatically slowing or stopping trains that are going too fast and could have helped if it had been installed on the line.

Investigators were looking to pull one of the black-box event recorders from the back of the train. The device contains information on the train’s speed and braking. NTSB vice chairwoman T. Bell Dinh-Zarr said it wasn't safe enough yet for investigators to extract the second recorder from the engineer's compartment because of the collapsed roof and the possibility of asbestos in the old building

More than 100,000 people use New Jersey Transit to commute from New Jersey to New York City each day. The NJ Transit portion of the Hoboken station will remain closed on Friday morning, potentially causing havoc for early morning commuters.

As investigators began their probe, the family of Fabiola Bittar de Kroon was in mourning after she was killed from falling debris at the station. She had recently moved to New Jersey from Brazil after her husband got a job with an international liquor company.

She had just dropped her toddler daughter off at daycare before rushing to catch a train, according to daycare director Karlos Magner.

"She was dropping off the daughter, I was closing up the stroller," he recalled. "We had a good talk for like a minute. And she said she was in a rush."

Shortly after, the NJ Transit train ran off the end of the track as it was pulling in around 8:45 a.m., smashing through a concrete-and-steel bumper. As it ground to a halt in the waiting area, it knocked out pillars, collapsing a section of the roof.

De Kroon was killed by debris, and 108 others were injured, mostly on the train, New Jersey Gov. Chris Christie said. Scores were hospitalized, some with serious injuries including broken bones.

Thomas Gallagher, the train’s engineer, was pulled from the mangled mess and was treated and released from the hospital. He was cooperating with investigators. Gallagher had worked for NJ Transit for 29 years, and a union roster shows he started as an engineer about 18 years ago.

New York Gov. Andrew Cuomo said investigators will determine whether the explanation was equipment failure, an incapacitated engineer or something else.

Some witnesses said they didn't hear or feel the brakes being applied before the crash. Authorities would not estimate how fast the train was going. But the speed limit heading into the station is 10 mph.

"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" as the roof fell, said Ross Bauer, who was sitting in the third or fourth car when the train entered the historic 109-year-old station, a bustling hub for commuters heading to New York City. "I heard panicked screams, and everyone was stunned."

Commuter Jim Finan, of River Edge, N.J., told Fox News' "America's Newsroom" that the train barreled into the station in "at full tilt" and "never slowed down."

William Blaine, an engineer for a company that runs freight trains, was inside the station and ran over to help. He told the Associated Press he saw the train's engineer slumped over the controls.

Finan described the crash as feeling like he was "in an off-road vehicle," adding, "It was bumpy. You were getting bounced around and then slammed forward."

Cuomo and Christie have both cautioned against jumping to conclusions about the role that the lack of positive train control played or didn’t play in the accident.

The NTSB has been pressing for some version of the technology for at least 40 years, and the industry is under government orders to install it, but regulators have repeatedly extended the deadline at railroads' request. The target date is now the end of 2018.

Over the past 20 years, the NTSB has listed the lack of positive train control as a contributing factor in 25 crashes. Those include the Amtrak wreck last year in Philadelphia in which a speeding train ran off the rails along a curve. Eight people were killed.

Even without positive train control, there are still safeguards in place in Hoboken.

NJ Transit trains have an in-cab system that is designed to alert engineers and stop locomotives when they go over 20 mph, according to an NJ Transit engineer who spoke on condition of anonymity because he was not authorized to discuss the accident.

Trains like the one in Thursday's crash also are equipped with an alerter system — a sort of dead man's device — that sounds a loud alarm and eventually stops the train if the engineer goes 15 to 20 seconds without touching the controls.

But it was unclear whether those mechanisms kicked in or would have made a difference if they had.

The Associated Press contributed to this report.