Two cars and the locomotive of an Amtrak passenger train carrying about 169 passengers derailed after colliding with a lorry in California's Central Valley, authorities said.
At least 20 passengers suffered minor to moderate injuries, authorities said.
The crash occurred when the driver of the tractor-trailer carrying cotton trash failed to yield and hit the train, authorities said.
The impact pushed the two passenger cars and the locomotive off the tracks south of Hanford, a farming town.
The train travelled about 600 feet after the collision before hitting a switchback and derailing, according to California Highway Patrol Officer Scott Harris.
Officials have not determined how fast the train or the lorry were going, but the average speed for Amtrak through the area is 70mph to 80mph, while the speed limit on the roadway where the truck was travelling is 55mph, Mr Harris said.
After the crash, metal pieces from the truck could be seen inside the train, which was covered by cotton seeds. Several pieces of luggage were also scattered about.
The injuries to passengers were described as bumps, bruises, scrapes and possibly broken bones by Kings County Assistant Sheriff Dave Putnam.