'RUNAWAY TRAIN'

As investigators searched for clues to the cause of the accident, some said it could and should have been prevented.

U.S. Senator Richard Blumenthal of Connecticut, a Democrat on a senate committee that includes transportation matters, said the crash was "hauntingly similar" to past tragedies involving insufficient or unsafe practices or equipment. Blumenthal has advocated for the roll out of the anti-collision system.

"This catastrophe was caused by a runaway train - traveling too fast and out of control. There is no excuse," Blumenthal said in a statement. He said there was an urgent need for better safety technology, new equipment and improved training.

The historic green-roofed Hoboken Station is served by NJ Transit commuter trains connecting much of New Jersey with the country's largest city, as well as the Port Authority Trans-Hudson subway-like system known as PATH, a light rail service and ferry service to New York.

In May 2011, a Port Authority of New York and New Jersey train crashed at Hoboken station, injuring more than 30 people. An investigation by the NTSB determined excessive speed was the main cause of the accident.

An NTSB official said the agency would look at similarities between that one and Thursday's crash.

The Hoboken crash was the latest in a string of fatal train crashes in the United States. The worst in recent years involved an Amtrak train that crashed in Philadelphia in May 2015, killing eight people and injuring more than 200.