A school bus driver was killed Sunday and several others were seriously injured after the bus veered off the roadway near Denver International Airport and crashed head-on into a concrete pillar, police said.

Police said the crash occurred shortly after 4 p.m. after the bus picked up members of the Legacy High School football team and then abruptply circled back to the airport.

The driver had picked up 28 students and four adults, airport spokeswoman Stacey Stegman told the Denver Post.

“(The driver) ran off the right side of the roadway," Denver Police Sgt. Mike Farr said. He added that they were all able to get out of the wrecked bus by themselves.

Police spokesman John White said the female driver died at the scene.

Police do not know why she circled back to the airport, White said. Three school buses were leaving the airport, police said. The driver's name and age have not been released.

At least 18 people were being treated for their injuries at nearby hospitals, Adams 12 Five Star said.

Officials at Denver Health told KDVR-TV that they had five patients; two are in critical condition, two are in serious condition and one is in fair condition.

The station reported that six patients in fair condition were taken to Children's Hospital Colorado, while officials with University Hospital said they had five patients, but it’s unclear what their conditions are.

Medical Center of Aurora said they had two walk-in patients who had minor injuries.

Uninjured students gathered with parents Sunday evening inside the airport, the Post reported. Police were interviewing the football players about the crash.

Legacy High School is in Broomfield, Colorado, and is part of Adams 12 Five Star Schools. The Post reported that the football team from Legacy played Chino High School on Friday night in California.

An official with DIA tweeted that all passenger pickups were taking place on Terminal West because of the crash on the east terminal.

The Adams 12 Five Star schools is a public district that serves suburbs north of Denver, including Broomfield, Federal Heights, Northglenn, Thornton and Westminster.

The Associated Press contributed to this report.

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