Adacia Avery Chambers is pictured in this booking photo provided by the Stillwater Police department, in Stillwater, Oklahoma, Oct 24, 2015. [Photo/Agencies]

The suspect does not appear to have been a student at Oklahoma State University, Gibbs said. The mayor's statement said she was a resident of Stillwater.

"At first we thought it was part of the show," Konda Walker, a 1991 graduate of OSU, told the local Stillwater News Press. "People were flying 30 feet (9 meters) into the air like rag dolls."

Megan Lantz of Ponca City, Oklahoma, told the Oklahoman newspaper that about 100 people were standing on the corner at the time the car, going between 45 and 50 mph (72-80 kph), struck the crowd.

"We were facing the parade and heard tires squealing and then started to hear the car hitting things and people and there was screaming and people running away," Lantz, 32, told the paper for a story on its website.

Hours later the car was still resting, crumpled, against a lamppost on Main street, the intersection littered with clothes, blankets, lawn chairs and water bottles belonging to the victims. Streets were blocked off and secured by members of the National Guard.

Oklahoma Governor Mary Fallin said on Twitter that she was en route to Stillwater and that her thoughts and prayers were with those affected.

After the crash, Oklahoma State University said it decided against canceling its homecoming football game, which went ahead as planned against Kansas and was dedicated to the victims. Some 25,000 students attend the university.

"We are shocked and heartbroken by this horrible tragedy. The Oklahoma State University Homecoming parade is the most wholesome of events and to have it marred in such a way is incomprehensible," the school's president, V. Burns Hargis, said.

"The Cowboy Family is devastated by events at this morning's homecoming parade," the school said on its website.