Three people were killed when an Amtrak train derailed near Seattle Monday and landed on Interstate 5, the Washington State Patrol said.

The National Transportation Safety Board (NTSB) said in a late night news conference that the train was travelling 80 miles per hour (mph) in a 30 mph zone, NBC News reported.

The NTSB said that data recovered from an event recorder at the rear of the train had provided information on the train's speed at the time of the derailment.

Amtrak said in a statement there were approximately 80 passengers, five crew members and one technician on board the Cascades Train 501, which was on the first day of service for the route. It was operating from Seattle and Portland, Oregon.

At a press conference, a Washington State Patrol spokesman confirmed three dead. Ten were seriously injured, and one was flown to a hospital. There were other injuries as well.

In the time immediately following the accident, authorities had reported at least six people dead, according to the Associated Press.

@PierceSheriff: Photos from scene of amtrak passenger train derailment

The Thurston County Sheriff tweeted about a "massive incident involving a train" derailing on the Mounts Road overpass midway between Tacoma and Olympia.

Five cars and two tractor-trailers on the highway were struck after 13 train cars derailed, some piling down off the overpass, around 7:40 a.m. PT, according to police. Several motorists were injured, but no fatalities among motorists were reported.

The train was moving more than 80 mph at the time of the accident. A U.S. official told the AP that track obstruction is seen as a possible cause.

Amtrak "temporarily suspended" service south of Seattle.

About 78 passengers and five crew members were on board. Amtrak recommended anyone with questions about family or friends aboard the train call 800-523-9101.

The mayor of DuPont declared a state of emergency in the city.