A video featuring a police officer appearing to aggressively body slam a 12-year-old girl has surfaced online, triggering widespread criticism. The video, shot through a mobile phone, showed Janissa Valdez, a 6th-grade student at Rhodes Middle Schoo in San Antonio, Texas, getting lifted up and thrown to the ground by police officer Joshua Kelm.

During the course of the incident, a crowd around the girl and the policeman fell silent after she was thrown to the ground, especially after a notably audible crack was heard the moment the 12-year-old's head hit the pavement. One of the students in the video was heard expressing concern about the girl.

"Janissa! Janissa, you OK? She landed on her face!," a student said.

After the girl was body slammed to the ground, the policeman proceeded to cuff her hands behind her back, before pulling her up and escorting her away. Prior to the violent incident, the girl had reportedly been involved in a verbal altercation with one of her peers.

Responding to the incident, the San Antonio Independent School District stated that it has begun investigating. District spokeswoman Leslie Price stated that the administrators have been very disturbed about the contents of the video.

"The video is very disturbing. We immediately launched a formal investigation, which is being conducted by both district police and administration," she said.

Kelm, a non-lethal weapons instructor before his stint in the school district, was reportedly placed on paid leave after the incident. He started working for the district police in 2015.

Judith Browne Dianis, co-director for Advancement Project, a civil rights organization condemned the policeman's actions.

"It is unconscionable for a 12-year-old student involved in a verbal altercation to be brutalized and dehumanized in this manner. Once again, a video captured by a student offers a sobering reminder that we cannot entrust school police officers to intervene in school disciplinary matters that are best suited for trained educators and counselors," she said.

The girl's mother said that what disturbed her the most is the fact that Kelm did not even flinch when he hit her child. Even after she stopped moving after her head hit the concrete, he still proceeded to subdue her. She also stated that after the incident her daughter's right eye was bruised and swollen.

"You could actually hear her head hit the concrete. That's what hurt me the most. He didn't even seem like it bothered him. He still handcuffed her after she was unconscious," she said.

After being body slammed, knocked out and taken away in handcuffs, Janissa Valdez was suspended for two days.

Check out the video below.