Railroad vehicles fell from the top of a bridge on a highway in Washington State, causing casualties, police said.
The train derailed, causing vehicles to fall on the A-5 highway.
Photos from the scene showed rescue teams treating a number of people.
Some cars crashed on the highway after train cars fell on them, the police department of Pierce province said.
Administration spokesman Eddy Troyer told local media that there were a number of deaths while some passengers remained trapped inside the train.
Several motorists were injured on the highway.
Local media said the accident occurred on the first high-speed train linking Portland and Seattle.
The state governor declared a state of emergency in two provinces.
"There are multiple deaths on the train," said Ed Troyer, a spokesman for the provincial department.
The derailed vehicles collided with several cars on the highway. Aerial photographs showed the scattered train vehicles on the ground, on both sides of the bridge that holds the rail above the highway.
He said the fire department had taken many people from the train to hospitals.
Passenger Chris Carnes, who was on the train, said his train was overturned down the bridge and then stopped. "We could hear and feel the disintegration of the cars, and then the water came out of the roof," said passenger Chris Carnis.
"In order to get out ... we had to break the emergency window."
It is reported that 78 passengers and five crew members were on board the train.