There was no explanation as to why the two trains were traveling toward one another on the same track about a mile (1.6 km) east of the town of Goodwell, in an unpopulated area near the Texas state line.
About 50 volunteer firefighters from five nearby towns had been fighting the fire, which engulfed three locomotives and about 10 rail-cars, since the morning collision. Several small fires continued to burn in the train wreckage.
The only known survivor of the crash, a Union Pacific employee, escaped injury by leaping from the train when he saw a crash was imminent, police said.
Three other employees were missing and presumed dead, Trooper Betsy Randolph of the Oklahoma Highway Patrol said. Investigators will have to wait until the fires are extinguished and the wreckage cools before they can search for remains.
"We believe we'll find their remains in the wreckage if there's anything left to find," Randolph said.
Each train was being operated by a conductor and an engineer, Union Pacific spokeswoman Raquel Espinoza said.
Both trains were pulling long lines of rail-cars, with the northbound train packed with automobiles and the southbound train transporting containers, Harold Tyson, emergency management director of Texas County, Oklahoma, said.
One of the containers, not on fire, held resin solution, and water was being poured on that container as a precautionary measure, Espinoza said.
National Transportation Safety Board investigators arrived at the small airport in Guymon, Oklahoma, to lead the investigation, Randolph said. (Reuters)
