Cellphone video of a Barrow County high school student being slammed headfirst into a wall during a fight left a lot of questions about what led up to the incident.

The county’s sheriff now says his investigators have figured it out.

Sheriff Jed Smith told Channel 2 Action News that Iris Narens, who was taken to a hospital with a serious head injury, was the one who initiated the fight.

“The young lady that sustained the injury was the primary aggressor in the situation, and we can factually say that happened,” Smith said. “Not minimizing her injuries in any way. She was the aggressor. The other young lady defended herself.”

The two students were in math class at Winder-Barrow High School on Thursday. The other student, who has not been identified, said she knew the answer to a math problem, and the sheriff told Channel 2 that Narens wouldn’t allow her to pass her once they got out of class.

Narens’ mother, Chrisalena Pringle, told Channel 2 on Monday that the other student initiated the fight after her daughter corrected the girl’s math problem in class. She also said the girl called Narens a “racially charged” name, which Smith refuted.

“Nothing was racially charged in this incident,” Smith said, adding his department also found no evidence of bullying.

MORE: Cops find 'no evidence' of bullying after student has head slammed into wall

From there, Smith said Narens “took a swing” at the other student first, initiating the fight.

In cellphone video of the fight filmed by another student, Narens is shown struggling in the hallway with the other girl. She is pushed headfirst into a concrete wall, and a loud popping sound is heard. The video was widely shared on social media.

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“What you see in the video is only about four seconds, and you don’t see what happened prior to,” Smith said.

Pringle told Channel 2 her daughter suffered a skull fracture.

The Barrow County School System told AJC.com on Monday that Narens was “escorted to a classroom for further evaluation” after the fight when she was found sitting in the hallway alert. A staff member, described as having emergency training, evaluated Narens and said she was “not exhibiting any of the symptoms that would have indicated a call to EMS,” the school system said in a news release.

Pringle was contacted about 20 minutes later, and she told Channel 2 she knew something was seriously wrong with Narens after she went to check on her in the nurse’s office.

“When I see her in the nurse's office, I look at her and I saw that I might lose my child,” Pringle said. “She couldn’t walk, she couldn’t really talk, her eyes were fluttering.”

Disturbing cellphone video caught the confrontation between Iris Narens and another student at Winder-Barrow High School last week.

The school system’s statement said Narens’ parents were advised to take her for further evaluation. Pringle drove her daughter to a hospital in Winder, and from there she was flown to an Atlanta hospital. She is now recovering at home, according to Pringle.

“They should have called 911,” Pringle said of school staff. “She should not have been moved. She shouldn’t be getting in trouble in any way, shape or form.”

The school system did not release any details about the other girl involved in the fight, other than to say it issued “appropriate consequences.” Channel 2 reported that there is still a possibility for charges to be filed.

The school system called the incident “very unfortunate,” adding that it was handled “according to system policies and protocols.”

“We do not condone fighting or any type of violence in our schools or the recording of incidents, and we work actively to prevent it,” the statement continued. “We were glad to learn that our student is now home recovering. Violence, in whatever form it takes, has significant consequences and is never the answer to interpersonal conflict.”