The passenger train that derailed in the US yesterday was travelling 128km/h in a 45km/h zone, transport investigators said.
A National Transportation Safety Board spokesperson told journalists "it's too early to tell" why the train was travelling at such a fast speed, an estimate that came from preliminary information obtained from an event data recorder in the rear carriage.
The Amtrak train, which was likely carrying around 80 people, was travelling on a new route for the first time before plunging off a bridge onto a busy highway, leaving at least three people dead.
Thirteen of the train's 14 cars jumped the tracks near the town of DuPont, Washington State Patrol spokeswoman Brooke Bova said.
Amtrak said there were 86 on board, 80 of them passengers.
Five vehicles and two trucks were involved in the incident, and the highway was littered with fragments of the bridge and tree branches.
Some motorists were injured but none died, authorities said.
Around 100 people were taken to nearby hospitals.
Ten people have serious injuries and dozens have been released, the Washington State Patrol said.
It has turned over the investigation to the NTSB, whose members were on the scene.
Geoff Patrick, a spokesman for Sound Transit, which owns the track, said it had recently been upgraded to handle passenger trains, from its prior use for slow-moving freight trains.
Several hours after the crash, train cars remained dangling from the overpass, with others strewn across Interstate 5, a major West Coast route stretching from the Canadian to Mexican borders.
Cranes have been brought in to remove the carriages.
The derailment happened on the first day Amtrak trains began using the new inland route between the Washington cities of Tacoma and Olympia, part of a $181-million (€153m) project to cut travel time, according to an October news release from the state's transport department and Amtrak.
It was not immediately clear whether the derailment was connected to the new route. An NTSB member told reporters it was too early to say what may have caused the crash.
The state transportation department said the track had undergone "weeks of inspection and testing" before yesterday's crash.
