In Sacramento, California, police have launched a criminal investigation into a white police officer who was caught on video slamming a black man to the ground and pummeling him, after stopping the man for allegedly jaywalking. Cellphone footage, as well as newly released police dash-cam video, shows the officer—whose name has not been released—tackling and then repeatedly punching 24-year-old Nandi Cain Jr. in the face.

Naomi Montaie: “No, you’ve got to stay right here. You can’t. You can’t. Hey! Hey! Hey! Why you doing him like that? Wait! Wait! Wait! Hey! Hey! Hey! Hey! Why you beating him like that?”

The Sacramento Police Department on Wednesday called the officer’s behavior unprofessional and “disturbing.” The officer has been placed on paid leave, pending an investigation; after it’s completed, the Sacramento County district attorney will decide whether to press criminal charges.