El Paso police say the incident happened Thursday.
It started with a criminal trespassing call at a community center.
In the video posted on Facebook, the officer can be heard yelling, "Back up" twice to the group of boys, many of whom appear to be younger than 10.
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While attempting to detain one of the boys, the officer puts his knee onto the side of a boy's head before a colleague helps the officer drag the detained boy onto the street.
Meanwhile, the group of teens and kids gather around the officer, with some of them cursing at him.
Then you can see the officer pointing a gun at them.
The police department is investigating whether the officer violated any procedures.
He's been with the police department for four years.