The passenger train that derailed in Washington state was traveling 80 miles per hour in a 30 mph zone, transport investigators said late Monday.

Bella Dinh-Zarr of the National Transportation Safety Board told journalists "it's too early to tell" why the train was traveling at such a fast speed, an estimate that came from preliminary information obtained from an event data recorder in the rear locomotive.

The Amtrak train, which Dinh-Zarr said was likely carrying some 80 people, was traveling on a new route for the first time before plunging off a bridge onto a busy highway, leaving at least three people dead.