IRVING, Texas (AP) — At least two people were killed and more than 40 were hospitalized after a charter bus careened off a North Texas highway and flipped onto its side Thursday, drawing a large emergency response as rescue crews struggled to reach victims inside, authorities said.

The Cardinal Coach Line bus was on its way to a casino in Oklahoma when it suddenly weaved across the busy highway and struck two concrete barriers before toppling over in the center median, witnesses said. The wreck occurred along President George Bush Turnpike in Irving, just east of Dallas/Fort Worth International Airport.

"We ended up swirling and weaving and then ended up on the side," passenger Daniel Risik, 73, told The Dallas Morning News. "People were screaming and hollering, a very traumatic situation to say the least."

The bus was carrying about 45 people, most of them senior citizens, law enforcement officials said. Risik said most of the passengers weren't wearing seat belts.

"People were piled on top of each other," he said. "It was unbelievable. A lady had pinned me. Rescue got there and started pulling people out of a roof emergency hatch. People were hollering, screaming, there was blood all over the place. It was unbelievable."

Texas Department of Public Safety Trooper Lonny Haschel confirmed that two people were killed. More than three dozen people were being treated at local hospitals, many of them suffering from fractured bones, hospital officials said.

Emergency vehicles could be seen swarming the bus as it lay in the grassy center median, and ladders were being used to pull passengers from broken windows. Witnesses said one person appeared to be pinned by the bus, which had picked up the passengers in Fort Worth.

A man who answered the phone at Cardinal Coach's offices in Mansfield, just south of Dallas, confirmed that one of the company's buses was involved in the Irving accident. But said he didn't have time to talk because he was trying to gather information about the crash.

Cardinal Coach has reported no crashes in the last two years that resulted in deaths or injuries, according to the Federal Motor Carrier Safety Administration. The company operates five buses and employs seven drivers, records show.

Law enforcement officers were interviewing bus passengers and other drivers who witnessed the crash. The wreck occurred near an interchange with a second highway, snarling traffic for several miles.

A spokeswoman for Baylor Medical Center in Irving said 14 patients arrived at the hospital following the accident. Officials at Las Colinas Medical Center in Irving confirmed another six patients were there, though details weren't immediately available on their conditions.

Another 15 patients were transported to Parkland Memorial Hospital, including the driver of the bus, and another victim was airlifted to a fourth hospital in critical condition, hospital officials said.

Public transportation buses with Dallas Area Rapid Transit were used to transport some passengers with lesser injuries.

The National Transportation Safety Board is sending investigators to Irving, board spokeswoman Kelly Nantel said.

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