The officer was called to the Pearl Street scene after a free-running pit attempted to get to a dog being walked by its owner, who called police.
When the officer arrived, according to reports, he observed a pit bull properly chained in a yard.
A second dog, however, came from behind a camper.
The dog had a restraining tether but it was not secured to anything and the animal charged the officer, who felt he had no choice but to shoot it.
Police have responded to several calls in the past few days regarding loose, vicious dogs, including one Tuesday that had people trapped in their St. Joseph Street house while it sat on the porch.
In most instances, the impounding officer has been able to snare the canines.
Police reminded residents that allowing a dog to run free is against city code.