By RACHEL LA CORTE
Associated Press

TACOMA, Wash. (AP) - An Amtrak train making the first-ever run along a new route hurtled off an overpass Monday near Tacoma and spilled some of its cars onto the highway below, killing an undisclosed number of people, authorities said.

Seventy-eight passengers and five crew members were aboard when the train derailed about 40 miles (64 kilometers) south of Seattle before 8 a.m., Amtrak said.

Ed Troyer, a spokesman with the Pierce County Sheriff's office, said multiple people were killed aboard the southbound train, but no numbers were immediately available.

The sheriff's office said several vehicles on Interstate 5 were struck by falling train cars and multiple motorists were injured. No fatalities of motorists were reported.

Chris Karnes was on the train, three or four cars back from the front.

"I'm not sure what got hit. I'm not sure what happened," Karnes said.

Medical tents were set up in the highway median just south of DuPont.

"The only car that is on the tracks is the rear locomotive. There are several cars that are hanging over the overpass," Karnes said.

In a statement, Amtrak said the train that derailed was Train 501, offering service from Seattle to Portland.

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.

It left Seattle around 6 a.m., according to an Amtrak schedule, and was due in Portland about 3 1/2 hours later.

All southbound lanes of I-5 were closed south of Joint Base Lewis-McChord, and motorists were being warned to avoid the area.

The train was going 81.1 mph moments before the derailment, according to transitdocs.com, a website that maps Amtrak train locations and speeds using data from the railroad's train tracker app.

The maximum speed along the stretch of track, known as Point Defiance Bypass, is 79 mph, according to information about the project posted online by the Washington State Department of Transportation.

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Associated Press writers Sally Ho and Phuong Le in Seattle and Michael Sisak in Philadelphia contributed to this report.

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