Arizona police said an officer is being investigated after video surfaced that shows him striking a woman in the face during an arrest  Flagstaff police said in a news release that Officer Jeff Bonar was placed on leave pending the probe.

They said, “Our agency is very concerned by what is depicted in this video.”

Police said the incident occurred Wednesday as police arrested a “somewhat uncooperative” woman.

Video apparently shot by an onlooker and posted on Facebook showed her struggling with two officers.

At one point, one of the men struck or punched the woman in the mouth area. She was eventually placed in a squad car.

There was no word on what prompted the arrest, but Arizona Republic reported it spoke with a man who identified the woman as his girlfriend and that police indicated she faced an arrest warrant.