A train which derailed in Philadelphia on Tuesday night, killing at least seven people was travelling at over twice the speed limit when the driver hit the brakes.
Although the black box recorder still needs to be fully analysed, investigators know the speed was too fast for the stretch of track.
Robert Sumwalt of the National Transportation Safety Board said:
“Maximum authorised speed through this curve was 50 miles per hour (80 kilometres per hour). When the engineer-induced brake application was applied, the train was travelling at approximately 106 miles per hour (170 kilometres per hour).”
Seven carriages were derailed in the incident and more than 200 people were injured.
The authorities have still not accounted for every one of the 243 people believed to have been on board.
As well as the train’s speed, Investigators are also studying the condition of the tracks and signaling equipment.
The Amtrak Washington to New York service had stopped in Philadelphia’s 30th Street station prior to the derailment which happened 20 minutes later.
Police are still waiting to question the engineer who was injured in the wreck.