Investigators continue to examine a black box recorder recovered from the train that smashed through a Hoboken, New Jersey, station at the height of Thursday's morning rush hour, killing one woman and injuring more than other 100 people.
The cause of the crash is still unknown, though the recorder, recovered late Thursday, could tell investigators details about the train, such as how fast it was going, and use of brakes, which may indicate why the train failed to stop.
A second recorder, which could give investigators more clues, has not yet been recovered.
"We've started the process and it's ongoing," said Christopher O'Neil, spokesman of the National Transportation Safety Board. "There are some structural issues there, and the structure is unsafe, potential for collapse, that kind of thing. So that has to be resolved. We want to get there as quickly as possible, but we want to get there safe," O'Neil said
At least a dozen people injured in the crash remained in hospitals Friday, two of them listed in guarded condition.