Four people have been killed after a freight train hit a float during a parade honouring wounded military veterans.
The crash, which also left 16 people injured, happened on a railway crossing in the city of Midland, Texas.
City spokesman Ryan Stout said six people are being treated at Midland Memorial Hospital, including one in a critical condition.
The crash site in an industrial area was cordoned off by police as rescue crews and investigators worked at the scene.
Midland Police Chief Price Robinson told local media: "I'm standing out here now. It’s hard to look at.
"It’s a very tragic event, very unfortunate."
The float was one of two carrying veterans from the Iraq and Afghanistan wars, some who suffered major injuries in combat, and their partners.
Some people managed to jump clear before the train hit, police said.
Witnesses described the panic as the locomotive's horn sounded.
"My daughter said, 'Momma, the train is coming!' Patricia Howle told KOSA-TV.
"People were jumping off, trying to get off that trailer and the truck was still rolling.
"People on the trailer saw the train coming and they were flying in every direction," she added. "I covered my face. I didn't want to see."
Hours after the accident, a float was still sitting near the train tracks, a white poster board on its side and about a dozen empty chairs sitting on top.
The US marked Veterans Day earlier this week, and the parade was part of an event to honour wounded veterans.
It was scheduled to end at a "Hunt for Heroes" banquet before the wounded service members were to be treated to a deer-hunting trip.
A spokesman for railway operator Union Pacific said it was not clear if the train crew had seen the float approaching the crossing but that they had been sounding their horn before the collision.
He added that the crossing gate and lights were working at the time.
National Transportation Safety Board spokesman Peter Knudson said the agency was investigating.