Investigators have no explanation yet for the catastrophic NJ Transit train crash that killed one woman and injured 114 people Thursday morning. So far officials have only acknowledged that the train was traveling at a high rate of speed when it arrived at Hoboken Terminal at 8:45 a.m. and proceeded to plow through the concrete and metal barrier at the end of the track. According to some witnesses, the front of the train became airborne as it crashed into the station.

The train "flew through the air," said NJ Transit employee Michael Larson, who described the ensuing scene as "horrifying." Train engineer William Blaine, who was on special duty in Hoboken at the time of the crash, tells USA Today that the moment of impact sounded "Kaboom! Like a bomb... At first you freeze, like you can’t believe what’s happening in front of you, and then... and then... you run."

Blaine ran toward the crash scene—some of the station's structural supports had shattered, bringing the roof crashing down. The majority of the injured were inside the crowded rush hour train, but as he ran toward the wreckage, Blaine says he nearly tripped over the body of Fabiola Bittar de Kroon, a 34-year-old New Jersey woman who was killed as she stood on the platform when the train crashed. "She was gone," Blaine recalled.

Blaine tells USAToday he saw the train's engineer "slumped over" in his seat in the front of the train. "The only thing I can think of is: Maybe he passed out or had a heart attack."

The engineer, who was released from the hospital Thursday afternoon, has been identified as 48-year-old Thomas Gallagher of Morris Plains, N.J. Sources tell NBC NY that Gallagher had no "red flags" in his history prior to the crash—no medical episodes, criminal history, or other infractions. Governor Chris Christie told reporters yesterday that Gallagher is cooperating with investigators, and Gallagher's father said his son had worked for NJ Transit for 19 years.

Passengers on the train say nothing seemed unusual until the moment the crash, when the lights went out and the train flew into the station. Bhagyesh Shah was in the second car; he tells the NY Times, "We were thrown off our feet. The train just didn’t stop. It just kept going and going and going."

The scene in the station was reportedly chaotic, with bloodied passengers trying to escape the mangled wreckage through emergency windows, while others remained stuck inside the train or pinned by debris. "I’ve never seen that kind of fear. It was awful,” Rick Ciappa, a safety inspector for New Jersey Transit, tells the Times. “Everyone was just completely stunned and terrified."

The National Transportation Safety Board is leading the investigation, and so far there's no indication that the cause of the crash was anything but accidental, either due to mechanical failure or human error. Experts tell NJ.com that the Hoboken Terminal "is antiquated... and unlike other area stations relies solely on the engineer to stop the train."

New Jersey Senators Cory Booker and Bob Menendez immediately blasted NJ Transit for not equipping trains with Positive Train Control, a sensor system that automatically forces trains to slow down in high-risk situations. In its 2015 annual report NJ Transit said that it had begun testing PTC in action and would begin installing hardware along tracks this year “when design plans are finalized." It is so far unclear if PTC would have prevented Thursday's crash, but Congress has passed legislation requiring freight and passenger railroads to install the technology. Today the Times reports that NJ Transit is "leaderless and underfunded":

The third-busiest commuter system in the country, New Jersey Transit has been operating without an executive director for nearly a year, its board of directors has not met for three months and it has not explained how it will close a $45 million gap in its budget this year. Last month, two of its buses collided in downtown Newark, leaving two people dead.

The cause of the fatal train crash has not been determined. But whether it proves to have been a case of human error or of mechanical failure, it is sure to focus more attention on a transit agency that has been operating in secrecy.

New Jersey Transit’s management “has been told to go into a bear cave and disappear until told to come back out,” said Martin E. Robins, a former deputy executive director of the agency. “We don’t know anything about what’s going on.”

Friday morning's commute was expected to be a rough one for New Jersey residents headed into NYC. There is no NJ Transit service in or out of Hoboken Terminal, which may have structural damage beyond what is visible following yesterday's crash. Investigators are concerned that the historic building may have released asbestos into the air when its canopy collapsed.

"We will only proceed to inspect the cars when it is safe to do so," a NTSB official told NJ.com. "It may be tomorrow afternoon before we can safely do that, but we will be proceeding with other aspects of the investigation until then."

Here's NJ Transit's information on service changes and alternative transportation options, and the Times has a travel guide.