The incident occurred around 5:00 p.m. along the 400 block of Sentner Street in Philadelphia's Lawncrest section.
Initial reports say a pit bull managed to either get through or over a fence and kill a neighbor's poodle.
The neighbor, an off-duty officer, then shot and killed the pit bull.
Pennsylvania SPCA Animal Rescue responded and retrieved both dogs.
Officials have not released any further information at this time.