Three people were murdered and 12 others were injured late Saturday in Philadelphia's crowded South Street entertainment district, where numerous people are thought to have opened fire.
It was unclear whether the officer's target, the alleged gunman, or anybody else was hit by the police shots.
The target escaped without being identified, according to a statement released by the Philadelphia Police Department on Sunday afternoon.
According to police, at least five persons opened fire in an attack sparked by a street brawl. They stated two firearms were found, but no suspects had been apprehended.
At 11:31 p.m. Saturday, the shooting officer, who was one of two on foot patrol nearby, saw at least one gunman fire into a gathering near South Street's intersection with South American Street, according to the police department.
Multiple mass shootings occurred in the United States for the second weekend in a row.