SAN ANTONIO, Texas -- A police officer for a San Antonio school district has been placed on paid leave after a video shows him slamming a sixth-grade girl to the ground.

San Antonio Independent School District is now investigating the incident, which occurred on March 29 at Rhodes Middle School, the San Antonio Express News reports.

The school district didn't become aware of the of the incident until a video was posted online Tuesday, reports say. It placed officer Joshua Kehm on leave on Wednesday morning.

The Express News reports Kehm intervened when two female students became "verbally aggressive" at about 4 p.m. on March 29. On the video he can be seen grabbing Janissa Valdez, 12, and holding her before picking her up and slamming her to the ground.

Students can be heard telling Janissa to "chill" just before she is slammed to the ground. A group of students also tell KSAT Channel 12 that Kehm was seen listening to the girls and was trying to end the confrontation peacefully. They tell the station that Kehm was kicked several times, although Janissa denies kicking the officer.

Janissa tells WOAI Channel 4 she doesn't remember getting thrown to the ground. She had some swelling above her eye after the incident but was not seriously hurt.

She says she was not going to fight the other student.

"I was going up to her to tell her let's go somewhere else so we could talk but that's when the cop thought I was going at her," Janissa says.

School district spokesperson Leslie Price tells KSAT a formal investigation is under way.

"We need to find out the details as to what occurred, but I can say that we will not tolerate excessive force in this district," Price says.

Gloria Valdez, Janissa's mother, says she's angry after seeing the video, but she also tells the Express News her daughter has been in fights before and has had previous encounters with the other student. She says her daughter has been bullied during the school year.

Janissa was suspended for two days after the incident but has not returned to school, KSAT reports, because of concerns about how other students might react.

"I just want something done," Gloria Valdez tells the Express News. "Because he could go back and do it again to my daughter or another student."