By Matt Petrillo

WILMINGTON, Del. (CBS) — Caught on camera, the arrest of a Wilmington man wanted by police for harassment allegations is sparking controversy over how it was handled. The city’s mayor is now responding to the video.

Wilmington police say that officer is now on administrative leave pending the outcome of an internal investigation.

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Security video shows a man identified as 44-year-old Dwayne Brown giving money to a cashier at 3 C’s Food Market in Wilmington’s Southbridge neighborhood back on Tuesday, Sept. 21.

Shortly after, Wilmington police say one of their own officers walks in. The two appear to exchange words. Then you can see the officer grab Brown by the arm.

Moments later, the officer pushes Brown’s body against the cashier’s barrier before banging his head against it.

“Deeply concerning,” Wilmington Mayor Mike Purzycki said.

The Wilmington mayor has also seen the video but says he’s limited in what he can say about it.

“There’s due process that everybody’s entitled to. We want to respect all the parties involved,” Purzycki said.

But to Coby Owens of the Delaware NAACP, the video is clear.

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“There was no reason for the officer to use that much force, to bang his head on the counter and then to take him down to the ground like that,” Owens said.

Wilmington police say officers initially received a call from a day care center about a man who had been making sexual comments toward staff, even in front of children.

Police identified that suspect as Brown before finding him inside the convenience store.

Brown now faces harassment and other charges.

But in a statement, Wilmington police added: “We will conduct a thorough investigation and take any necessary action to ensure all of our members adhere to the highest standards of service to our community.”

Eyewitness News also showed the video to Philadelphia-based attorney Jordan Strokovsky, who does not know the officer or the suspect involved in the incident.

“The officer should address the situation as it’s going down inside that store. And that man appeared harmless,” Strokovsky said.

Owens, the man who posted the video online, says he wants to see the officer fired.

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Wilmington police have not released the officer’s name as they investigate the incident.