A 12-year-old girl will face charges in a fight captured on video in a classroom at Sunnymead Middle School in Moreno Valley, less than one month after a boy at another middle school in the school district died after authorities said he was attacked on campus.

The Riverside County Sheriff’s Department said the late Wednesday morning incident at Sunnymead involved two 12-year-old girls, one sustaining injuries not serious enough for hospitalization.

The other girl “was determined to be the aggressor,” and will face unspecified charges. She was not arrested, Deputy Robyn Flores said Thursday.

The Moreno Valley Unified School District said extra deputies were on the campus Thursday “as a precautionary measure.” The district said the classroom’s teacher “followed protocol of intervening to stop the incident when it was safe to do so and she called for help.

“A campus security officer and an administrator responded in addition to a school resource officer,” district spokeswoman Anahi Velasco said.

Moreno Valley Unified school superintendent Martinrex Kedziora held a news conference Thursday afternoon to express his dismay over the attack.

“What I’ve seen — what we’ve all seen — in those videos is unacceptable, and I want to assure you that what you see in those videos are not true representatives of Moreno Valley Unified School District,” he said.

Moreno Valley Unified has solid anti-bullying policies, he said, but it will continue to re-evaluate them.

“It is very disturbing because this time, it’s in the classroom,” said Moreno Valley City Councilman David Marquez said of the video Thursday.

“What is going on in the school district?” Marquez asked rhetorically. “I have very good communication with the trustees and the superintendent, but my concern is, ‘what’s going on?’ “

The video shows a girl walking into view with someone saying, “What’s up, honeys?” As the girl approaches another girl seated at a table, a woman wearing a lanyard with ID tags who appears to be a teacher, and another person, try to intervene.

But she gets around them by stepping up on a table, and then sets into the girl she appeared to be targeting, with a struggle among several students, and screaming heard.

An adult voice can be heard, “Go call campus security!” A boy shouts, “Shut the door!” And an adult voice can be heard saying, “Break it up!” as the video ends. It is difficult to tell how many were directly involved in the incident.

The Southern California News Group is not using the video or stills from it because it shows minor children.

The incident took place in the same district where 13-year-old Diego Stolz was fatally injured in what sheriff’s deputies said was an attack by two other boys outside a building at Landmark Middle School on Sept. 16.

A video of the incident shows Diego’s head hitting a pillar after he is hit by one of the boys. The two students, both 13, have been charged in juvenile court with voluntary manslaughter and assault.

One of them denied the charges on Wednesday and will have a pretrial hearing Nov. 1. The second is expected to enter his plea to the petition on Oct. 15. The boys are not being identified because of their age.