LANCASTER, Pa. (CBS) — A Pennsylvania police officer is seen on video using a stun gun on a man as he’s sitting on a curb. Lancaster police says officers were called around 10 a.m. Thursday and told a man was confronting people with a bat.

Video posted to Facebook captured Officer Philip Bernot telling 27-year-old Sean Williams to sit on a sidewalk and stick his legs out. Bernot then uses his stun gun on Williams while the man is sitting, facing away from the officer.

Police told Lancaster Online another officer, Shannon Mazzante, arrived on the scene just after 10 a.m. and repeatedly told Williams to sit down on the sidewalk, but Williams didn’t comply. Bernot then arrived to assist Williams. Williams is seen sitting on the curb as the video begins.

Police said Bernot warned Williams that if he continued to refuse commands, the Taser would be used on him, according to Lancaster Online. Williams appears to move his legs closer to his body before he is Tased. Williams tells WGAL-TV he followed all directions and doesn’t know why he was shocked.

The website reports Williams had an outstanding criminal warrant for charges of possession of a controlled substance and public drunkenness, police said. Police reportedly said they found no bat at the scene.

Mayor Danene Sorace says she was upset by the video, and an investigation into the officer’s use of force is ongoing.

“Like you, when I saw the video I was upset by it and it is of great concern to me. We take the use of force very seriously,” Sorace said in the statement, according to Lancaster Online.