CHARLOTTE, N.C. -- All but one of the 36 students injured in a school bus crash on Interstate 77 Wednesday morning have been released from local hospitals.

The student who remains hospitalized underwent surgery and is listed in good condition.

N.C. Highway Patrol troopers are investigating the cause of the crash. Troopers say the Cabarrus County Schools bus driver may have missed her exit and overcorrected, or she may have been swatting a bee away when she lost control of the bus.

The activity bus carrying 58 passengers, including students and adult chaperones, overturned at about 10 a.m. on I-77 at the Brookshire Freeway.

NewsChannel 36

PHOTOS of the scene

"It was just scary. I thought I was going to die or something," said fifth-grader Kailey England.

The Cox Mill Elementary School students were headed to an overnight field trip to Camp Thunderbird on Lake Wylie when the driver, a teacher's assistant, lost control near an exit ramp.

"Our bus driver turned off the side of the interstate, and then she tried to turn it back on the road, and she tried to turn it back again because pulled across the whole interstate, and then the bus flipped over and fell on its side," England said.

"We went to the right and then we went back to the left really quickly, and I looked out the window and the guardrail was coming at us," said fifth-grader Ryce Felker. "I closed my eyes and when I opened them back up there was broken glass on the grass and pushed myself up, grabbed one of the luggage rails and got out."

Others needed help and drivers passing by gave it.

"Some of the other people that weren't even associated with us came over and helped us and we were all crying because we were shaken up. We were scared," Felker said.

Emergency crews set up a triage area in the highway median. At least eight students on stretchers were rushed by ambulance to area hospitals. Twenty more were taken to hospitals on a mass casualty bus for minor injuries.

"Just relieved that I got out of the bus and hopeful that some of my friends were OK," Felker said.

Highway Patrol troopers say the driver is traumatized. She was not hurt. Her own daughter was on the bus, too.

We're told the bus hit the exit sign, the guardrail and a light pole along the interstate.

A total of 81 students who were not hurt were taken by buses to the Charlotte-Mecklenburg Police Department to be reunited with their parents. The activity bus that overturned was following two other buses, also headed to Camp Thunderbird.

Reunions at CMPD headquarters were emotional for students and parents.

"I just couldn't think of anything but 'Just let her be OK. Let all the kids be OK,'" said parent Linda Bradford.

"I'll feel much better when I get my hands on him," said Pam Bregant, another parent, as she arrived at CMPD.

The kids received hugs from some parents they didn't even know. Many of them were still shaken up, especially those who were on the bus that flipped over.

"I thought it was a dream because I was like falling asleep sort of and then I landed on my friend," said student Kai Daniels.

Students who were on the other buses, not involved in the crash were scared, too.

"How could this happen? It was supposed to be a happy day, then this tragedy happened. It was just horrible," said student Alva Dempsey.

As the students got off buses at CMPD headquarters, some held hands, others were in tears, but happy their friends were OK.

Student Katie McClanahan was on one of the buses that didn't crash. Those students were rerouted to CMPD, not knowing what had happened.

"We were just like something had to happen. They said the bus flipped and a lot of our friends were on there and everybody was just breaking down crying," said McClanahan.

(NewsChannel 36 reporters Michelle Boudin and Anjanette Flowers contributed to this report.)