Federal and state investigators are set to return to the West Texas site of a prison bus crash that killed 10 occupants and left five others hospitalized in critical and serious condition.

The National Transportation Safety Board and Texas Department of Public Safety on Thursday will sift through the debris as they try to determine what may have contributed to the crash. The state Department of Criminal Justice bus skidded on an overpass, slid down an embankment and crashed with a passing Union Pacific freight train Wednesday, Ector County Sheriff Mark Donaldson said Wednesday.

Two corrections officers, including the driver, and eight inmates were killed. Another corrections officer and four other inmates were hospitalized.

"It's as bad as you can imagine," Odessa Fire and Rescue Battalion Chief Kavin Tinney told the Odessa American newspaper. "In 32 years, it's as bad as anything I've seen."

A prison system statement identified the dead as correctional officers Christopher Davis, 53, and Eligio Garcia, 45; and inmates Byron Wilson, 34; Tyler Townsend, 29; Jesus Reyna, 44; Kaleb Wise, 22; Adolfo Ruiz, 32; Michael Sewart, 25; Angel Vasquez, 31; and Jeremiah Rodriguez, 35.

The statement did not say which officer was driving the bus. Davis had more than 17 years of service with the Department of Criminal Justice, and Garcia had nearly 23 years. The inmates were serving sentences that ranged from one year for labeling unauthorized recordings to 20 years for drug possession with intent to distribute, according to online prison records.

Correctional officer Jason Self, 38, and inmates Terry Johnson, 22, and Damien Rodriguez, 22, were hospitalized in critical condition, the prison system said. Inmates Remigio Pineda, 34, and Hector Rivera, 37, were in serious condition.

The prisoners, who did not have seat belts, were handcuffed together in pairs, officials said. Some of them were ejected from the bus after it struck the train, said Trooper Elizabeth Barney of the Texas Department of Public Safety.

The prisoners did not have any leg restraints, said Jason Heaton, agency director for the region. The driver's seat had a seat belt, he said.

An earlier accident on the I-20 overpass may have contributed to the prison bus losing control, Donaldson, the sheriff, said. Donaldson also said the overpass was slick with ice.

A state prison system spokesman said the bus was new and had been placed in service only this past summer.

Jason Clark, a Department of Criminal Justice spokesman, said the bus was taking the inmates from the Middleton prison in Abilene to the Sanchez prison in El Paso, which is about 250 miles west of where the accident happened.

After the accident around 7:30 a.m., the white bus came to rest on its side, next to the railroad tracks, crumpled with heavy damage to its front and undercarriage. The top of the bus was caved inward.

The Union Pacific freight train with four locomotives and 58 cars came to a stop soon after. None of the cars derailed, but two containers at the rear of the train were damaged, said Mark Davis, a railroad spokesman.

The containers were carrying hundreds of parcels and packages, many of which were strewn along the tracks.

No Union Pacific employees were injured.

The train was traveling from the Los Angeles area to Marion, Arkansas.

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Associated Press writers David Warren, Terry Wallace and Diana Heidgerd contributed to this report from Dallas.