Story highlights Cell phone video shows a school officer slam a middle-school student to the ground

The girl's mother says the officer told her that "he did what he had to do at that moment"

The officer is on administrative leave pending the outcome of an investigation, the school district says

(CNN) An officer lifts a middle-school student into the air and slams her to the ground.

She lies motionless as he handcuffs her. Some students shout out; others laugh as she's escorted away.

The cell phone video, which spread rapidly after it was posted online this week, has sparked investigations by police and school officials in San Antonio, Texas, CNN affiliate WOAI/KABB reported

"It's very concerning. It's alarming to see this," San Antonio Independent School District spokeswoman Leslie Price told WOAI/KABB. "And while we want to get all the details, I want people to know that excessive force will not be tolerated in this district."

Gloria Valdez told the CNN affiliate that her 12-year-old daughter is the girl shown in the video.