LAWNDALE (WPVI) -- A suspect assaulted an off-duty Philadelphia police officer and stole his gun, authorities said.It happened around 2:30 a.m. Friday on the 6700 block of Martins Mill Road in the city's Lawndale section.Detectives said the officer was involved in a scuffle when the suspect stole his gun and took off running on Unruh Avenue.The officer was not seriously injured.