The Long Island Rail Road train was going more than 10 miles (16 kilometers) per hour when the accident occurred Wednesday at Atlantic Terminal, said a spokesman for the National Transportation Safety Board, Ted Turpin.
The track speed limit is five mph, he told a press conference.
The spokesman said the investigation was ongoing, and did not indicate why the engineer might have been speeding when the train slammed into a bumper at the end of the tracks at around 8:30 am (1330 GMT).
The driver remembers entering the station but was "unable to recall striking the end of the track," said Turpin.
The 50-year-old train engineer was finishing his overnight shift when the accident occurred. He told investigators he was not using his cell phone at the time.
He submitted to drug and alcohol testing, but results were not yet available.
Train accidents are not rare in the United States, where the rail system suffers from chronic underfunding. Investigators often take time to discern the precise causes.
Authorities emphasized how happy they were that the crash left no one dead or seriously hurt, given there were hundreds of passengers on board.
In September, a commuter train derailed during rush hour as it entered the station in Hoboken, New Jersey. One person died and 114 were injured.
An investigation into that incident, in which the train entered the station at an unusually high speed, is ongoing. Attorneys for the train engineer have said he suffered from sleep problems, which could have caused the accident.
