DUPONT, Wash.  — An Amtrak train making the first-ever run along a faster new route hurtled off an overpass south of Seattle at an estimated 80 mph Monday and spilled some of its cars onto the highway below, killing at least six people and crushing two vehicles, authorities said.

Seventy-seven passengers and seven crew members were aboard when the train derailed and pulled 13 cars off the tracks. At least 50 people were hospitalized, more than a dozen with critical or serious injuries, authorities said. No one on the highway was killed.

A website that maps location and speed using data from Amtrak’s train tracker app shows the train was going 81.1 mph (129 kph) about one-quarter mile from the point where it derailed, where the speed limit is significantly lower.

A track chart prepared by the Washington State Department of Transportation shows the maximum speed drops from 79 mph (127 kph) to 30 mph (48 kph) for passenger trains just before the tracks curve to cross Interstate 5, which is where the train went off the tracks.

The chart, dated Feb. 7, 2017, was submitted to the Federal Railroad Administration in anticipation of the start of passenger service along a new bypass route that shaves 10 minutes off the trip between Seattle and Portland.

It wasn’t clear how fast the train was moving when it derailed.

In a radio transmission immediately after the accident, the conductor can be heard saying the train was coming around a corner and was crossing a bridge that passed over Interstate 5 when it derailed. Dispatch audio also indicated that the engineer survived with bleeding from the head and both eyes swollen shut.

President Donald Trump used the deadly derailment to call for more infrastructure spending in a tweet sent about three hours after the accident. He said the wreck shows “more than ever why our soon to be submitted infrastructure plan must be approved quickly.” The accident happened on a newly completed bypass.

The train was making the inaugural run on the new route as part of a $180.7 million project designed to speed up service by removing passenger trains from a route along Puget Sound that’s bogged down by curves, single-track tunnels and freight traffic.