A COMMUTER train derailment and collision that left dozens injured outside New York City was not the result of foul play, officials say.
A fractured section of rail is instead being studied to determine if it is connected to the accident.
Officials described a devastating scene of shattered cars and other damage where two trains packed with rush-hour commuters collided in Connecticut, saying Saturday it was amazing no one was killed.
Seventy-two people were sent to hospital Friday evening after the crash, which damaged the tracks and threatened to snarl travel in the northeast corridor.
National Transportation Safety Board member Earl Weener said Saturday the broken rail is of substantial interest to investigators and a portion of the track will be sent to a lab for analysis.
Weener said it's not clear if the accident caused the fracture or if the rail was broken before the crash. He said he won't speculate on the cause of the derailment and emphasised the investigation was in its early stages.
About 700 people were on board the Metro-North trains when one heading east from New York City's Grand Central Terminal to New Haven, Connecticut, derailed at about 6:10 pm just outside Bridgeport, Connecticut.
Officials couldn't say when Metro-North Railroad service would be restored. The crash also caused Amtrak to suspend its passenger train service between New York and Boston.
National Transportation Safety Board investigators arrived Saturday and are expected to be on site for seven to 10 days. They will look at the brakes and performance of the trains, the condition of the tracks, crew performance and train signal information, among other things.