The Sacramento Police Department is formally investigating a viral video that purportedly shows one of its officers slamming a black man to the ground and beating him.

The officer, who is white, confronted Nandi Cain Jr., after he had allegedly been jaywalking, a violation in the state of California.

Naomi Montaie captured the incident, which took place Monday evening, on on her cellphone and posted the five-minute video on Facebook.

In the video, Cain can be seen speaking with an officer. He removes his jacket and drops it on the ground. The police officer charges Cain, grabs him, slams him to the pavement, and starts beating him. In the video, Montaie and a passenger can be heard shouting, “Hey!! Why you beating him like that?”

Sacramento Police Department released a statement saying the officer, a two-year veteran of the force, had “attempted to detain a pedestrian for allegedly unlawfully crossing the street.” A verbal dispute reportedly ensued. “The pedestrian questioned the officer’s validity to stop him, at which time a violent encounter occurred between the officer and the pedestrian.”

After the altercation, Sacramento Police continued in the statement, “the man was handcuffed and arrested for resisting arrest and issued an outstanding misdemeanor warrant out of Fresno County.” The statement said that Cain “began to violently kick the interior of the patrol car and had to be restrained by a leg hobble.”

Per department protocol, the incident is currently under investigation and the officer involved has been placed on leave.