Officials in the city of Lancaster, Pennsylvania are investigating after a video shows police using a stun gun on a black suspect while he was sitting on the ground. LNP, the daily newspaper in Lancaster, reports that Lancaster police responded to a 911 call Thursday morning stating a man approached a group of people with a baseball bat.

WCAU-TV in Philadelphia reports that police claim "Williams had wanted to fight with them and was also trying to keep a woman from entering her apartment."

Minutes later, police responded to the 911 calls.

Officers asked the suspect, identified as 27-year-old Sean Williams, to sit on the sidewalk. Police say Williams did not comply initially but finally sat down when backup arrived.

That's when a bystander began filming the incident.

The video shows that while Williams is sitting on the ground with his arms by his sides, he fails to follow officers' instructions to straighten and cross his legs simultaneously. After about 30 seconds of commands, an officer deployed a stun gun from inches away.

"No, he's not listening," the officer can be heard saying.

“Non-compliance is often a precursor to someone that is preparing to flee or fight with Officers," police said in a statement to LNP.

WCAU reports that Williams was arrested on an outstanding warrant of a controlled substance (PCP) and a public drunkenness charge. He was arrested, arraigned and released after posting bail.

Lancaster Mayor Danene Sorace released a statement via a Facebook video, saying the arrest video was of "great concern."

"We take the use of force very seriously. There is already an investigation that has already commenced regarding the use of force in this incident," Sorace said.

According to WCAU, police declined to say whether the officers involved would be placed on administrative leave.

Alex Hider is a writer for the E.W. Scripps National Desk. Follow him on Twitter @alexhider.