The US National Transportation Safety Board said it's too early to know if the crash was due to high speed.

Bella Dinh-Zarr, spokesperson for NTSB, said a team of 20 investigators will be at the scene later Monday evening.

US President Donald Trump also offered "thoughts and prayers" on Monday for those involved in a train derailment in Washington state.

Founded in 1971 and headquartered in Union Station in Washington, DC, Amtrak is a passenger railroad service that provides medium- and long-distance intercity service in the contiguous United States.

Amtrak serves more than 500 destinations in 46 US states and three Canadian provinces with more than 300 trains running over 21,300 miles (34,000 km) of track every day.

In fiscal year 2016, the company, which employs more than 20,000 people, served 31.3 million passengers and earned about 3.2 billion US dollars in revenue.

Nearly two-thirds of its passengers come from the 10 largst metropolitan areas.