An Amtrak train derailed on an overpass in Washington, authorities said Monday.
CBS News affiliate KIRO-TV reports first responders are treating the derailment as a mass casualty incident.
CBS News correspondent Kris Van Cleave reports first responders have set up triage tents at the scene.
A spokesperson with St. Joseph's Medical Center says a total of 77 patients are being transported to hospitals in Pierce and Thurston counties. Four of the patients will be treated for severe injuries.
Amtrak train 501, which departed shortly before 8 a.m. local time from Tacoma, was part of a new service that launched Monday morning. The train is able to carry up to 250 people, but Amtrak said there were approximately 78 passengers and five crew members on board at the time.
The service was supposed to be rated for a maximum speed of 79 mph for the section where it derailed in DuPont, according to passenger Chris Karnes.
Karnes, who was on board the train when it derailed, said at least seven cars derailed from the tracks. The emergency doors were not functioning correctly, which forced passengers to kick out train windows to exit.
"We had just passed the city of DuPont and it seemed like we were going around a curve," Karnes said. "All of a sudden, we felt this rocking and creaking noise, and it felt like we were heading down a hill. The next thing we know, we're being slammed into the front of our seats, windows are breaking, we stop, and there's water gushing out of the train. People were screaming."
"The tracks for this line were supposed to be upgraded to be able to handle higher speeds," he continued. "I'm not sure what happened at this juncture."
The cause of the derailment remains under investigation.