LOS ANGELES, Calif. — The Los Angeles County sheriff says he has concerns about tactics deputies used to detain three Black teenagers at gunpoint after the mother of one said they had been threatened by a man holding a knife.

Sheriff Alex Villanueva said Monday that he had seen a video of the incident, which was uploaded by one of the teens' mothers to her Instagram profile last week.

The mother wrote that the man tried to stab the boys but the deputies handcuffed her son and the others.

The video shows the deputies holding out at least two handguns and one long gun.

A sheriff’s spokeswoman says the teens were not arrested and were released at the scene.