The San Bernardino County sheriff has ordered an investigation after deputies were recorded beating and kicking a man who fled in a car and then on horseback.

John McMahon calls video of Thursday's confrontation disturbing.

A Sheriff's Department statement says deputies tried to serve an identity-theft warrant on 30-year-old Francis Pusok of Apple Valley.

Pusok allegedly sped off in a car that he abandoned, then stole a horse in Hesperia and galloped through rugged terrain.

Authorities say the horse threw Pusok.

Deputies arriving by helicopter jolted him with a stun gun.

KNBC-TV (http://bit.ly/1H8UC3D ) says its video shows deputies kicking and punching Pusok dozens of times in the head, groin and elsewhere as he lay on the ground.

He was taken to a hospital with unknown injuries.