DALLAS -- A fire in a chartered bus filled with elderly Hurricane Rita evacuees, including some who used oxygen, killed 24 people and injured several others near Dallas Friday.

Authorities said the bus apparently caught fire due to a mechanical problem, and that oxygen tanks then started exploding on gridlocked Interstate 45. Dallas County Sheriff's Sgt. Don Peritz said the brakes may have been on fire, leading to the explosion.

Peritz said deputies couldn't get everyone off the flaming bus. The bus was carrying 38 residents and six employees of the Brighton Gardens nursing home in Bellaire to Plano, according to Sunrise Senior Living, the McLean, Va., company that owns the center.

They had been on the road since Thursday.

Nine people between the ages of 78 and 101 were sent to Parkland Hospital, where all except one were believed to be OK with only minor burns. One woman suffered severe smoke inhalation and was in critical condition Friday morning.

Three women and one man were sent to Baylor Medical Center, where they are listed in fair condition.

The bus, surrounded by police cars and ambulances, was engulfed with flames and later reduced to a blackened, burned-out shell with large blue tarps covering many seats.

Peritz said permission was given to remove the charred hulk of the bus from the northbound lane with the bodies still on board, shrouded by the tarps. The crowded interstate is a primary Hurricane Rita evacuation route.

Peritz said the driver and arriving deputies tried to rescue as many passengers from the bus as possible but couldn't save everybody. He said the driver survived.

"It's my understanding he went back on the bus several times to try to evacuate people," he said.

The fire caused a 17-mile backup on a freeway that was already heavily congested with evacuees from the Gulf Coast.

Northbound lanes on I-45 were reopened late Friday morning. State officials said traffic was being diverted off I-45 onto U.S. Highway 287 at Ennis, about 30 miles southeast of Dallas.

I-45 stretches more than 250 miles from Galveston through Houston to Dallas.

Bellaire city officials defended the decision to evacuate the elderly patients from the Brighton Gardens nursing home.

“(Evacuating was) the right decision," Bellaire Mayor Cindy Siegel said. "Brighton Gardens was following their evacuation procedures. Just 24 hours ago, (Houston) was expected to take the brunt of Hurricane Rita, Brighton Gardens was doing their job to get their patients to safety"

"Unfortunately, this is a tragedy that we are very saddened by. I don’t think anyone can ever plan for every tragedy that can occur,” Siegel said.

Siegel said relatives of residents of Brighton Gardens should contact the nursing home directly at (713) 665-3888 or (800) 786-7471 to obtain information on their conditions.

Nurse Saw Fire, Explosion

A nurse who was driving behind the bus said she saw it start to smoke, and then pull to the side of the road.

Tina Jones said, "I saw the smoke, and then there was an explosion."

She pulled over and helped treat minor injuries. And she said she saw at least six bodies.

After witnessing the horror, Jones said she'll "probably go home and have a good cry."

Hurricane Rita

Forecasters say Hurricane Rita remains an extremely dangerous Category 4 storm with 140 mph winds. It's turned to the right more than anticipated, meaning it may spare Houston and Galveston, Texas, a direct hit.

Tornadoes, a big storm surge and rough waves are forecast. Click here for that full story.