The Vallejo Police Department is facing questions of excessive force because of cell phone video showing an officer hitting a man during an arrest and pulling his gun on a crowd of onlookers.

Vallejo Police have not said what led up to the arrest.

KTVU has been told the officer was apparently chasing after a man who was acting erratically and things escalated. Some believe the officer went too far during the arrest.

Tensions were running high as the Vallejo Police officer struggles to take a man into custody after tackling him in the middle of the street.

The video, posted online over the weekend, shows the officer punching the man in the head and then later striking him several times with either his baton or flashlight.

You can hear the officer yell for the man to give him his hands. On the video you can hear bystanders questioning the use of force.

As back up arrived at the scene, the original responding officer pulled his gun and pointed it in the direction of onlookers before re-holstering his weapon.

The officer can then be seen striking the man three more times. It’s unclear what led up to this violent encounter.

We’re reaching out to the Vallejo Police Department to find out more about this investigation.