WILMER, Texas (AP) -- A bus ferrying nursing home residents away from Hurricane Rita caught fire and exploded Friday while stuck on a gridlocked highway south of Dallas, killing as many as 24 people.
Early indications were that mechanical problems, possibly with the vehicle's brakes, sparked the fire, which was then fed by explosions of passengers' oxygen tanks, Dallas County sheriff's spokesman Don Peritz said.
Authorities believed 24 people were killed, but that number could change, Peritz said. The medical examiner's office was still working to determine the number of fatalities.
The bus was carrying 38 residents and six employees of the Brighton Gardens nursing home in Houston to another home in Dallas owned by its parent company, Virginia-based Sunrise Senior Living.
Sheriff's deputies and the bus driver tried to rescue passengers but could not get everyone off the bus as it became engulfed in flames. The vehicle was reduced to a blackened, burned-out shell, with large blue tarps covering the bodies.
Tina Jones, a nurse, pulled over and helped treat the injured after witnessing the explosion. She said she saw at least six dead bodies.
''I'll probably go home and have a good cry,'' she said.
Fred Witte, 74, said he heard three explosions from his property about 150 yards from where the bus caught fire.
''I was right there at the corner, and I felt the pressure,'' he said of the first blast.
The fire caused a lengthy backup on Interstate 45, which was already congested with evacuees from the Gulf Coast. The interstate was shut down for about four hours but reopened after authorities made the unusual decision to move the wreckage so hurricane evacuees could get through.
''You have thousands of people who are in their vehicles trying to escape,'' Peritz said.
Sunrise Chairman and Chief Executive Paul Klaasen said in a statement that the company's ''primary concern is for the safety of our residents, and we are shocked and saddened that this event occurred during our evacuation.''
Ten patients, including the driver, had been treated and released at hospitals by Friday afternoon. Four patients remained hospitalized, one in stable condition and three in fair condition.
The National Transportation Safety Board sent a team of specialists and investigators to the scene.
The bus that caught fire was traveling with another bus carrying 15 people. The second bus arrived safely in Dallas, company spokesman Jamison Gosselin said.
Interstate 45 stretches more than 250 miles from Galveston through Houston to Dallas. The crash site was roughly 17 miles southeast of downtown Dallas.
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Associated Press writers Schuyler Dixon and Zinie Chen Sampson contributed to this report.
