The video is difficult to watch. In it you can see an officer straddling a man on the ground and striking him in the face with a closed fist several times.
It's caused concern among lots of residents.
"When I see the video it makes me mad, it makes me upset," said resident Shaun Hudson. "This is somebody that we're supposed to trust that's doing these types of things and beating people up."
Vallejo Police Chief Andrew Bidou released a short statement on Monday that reads:
"It is important to note that the Vallejo Police Department reviews every instance of use of force by our officers. We are aware of the attention this particular incident has gained and therefore I have ordered a full and complete investigation to be conducted. I have complete confidence in our Internal Affairs Division and our use of force experts who will conduct this investigation. Upon completion, I will thoroughly review the entire investigation and personally make a final determination. I ask for your continued patience as proceed through this process."
According to police, officers were called to the Valero gas station because 23-year-old Vacaville resident Dejuan Hall was frightening employees.
ABC7 News spoke with the owner of the station off camera, who said the man was trying to buy a Greyhound bus ticket to Sacramento. When his credit card was declined, the owner says the man lost his temper and began pointing his fingers at employees like he had a gun while shouting, "I'm God, I'm God."
In the video you can hear the man shouting the same thing.
We showed it to police training expert Don Cameron who said, "I think any use of force is tough to watch. But the fact of the matter is, all the guy had to do, like the officers said, was give me your hands. And if he would have given him his hands that's fine, but the guy kept fighting with him."
He says the officer was following his training.
The police department has not told us if the officer will remain on duty while the investigation of this incident continues.
Police say Hall was booked on suspicion of being under the influence of a controlled substance, resisting arrest, resisting or threatening an officer with force, and a probation violation.
WARNING GRAPHIC LANGUAGE: The full videos have been posted in three parts on Facebook here, here, and here.