The Lancaster Intelligencer-Journal reports that police in Lititz received a call at about 3 a.m. Saturday from a woman who said she needed help. That's just outside Lancaster.
Police responded, and the unidentified man allegedly threatened an officer and tried to grab his gun. Police reportedly used a stun gun, but the man continued making threats and advanced on the officer with a large knife.
The investigation is ongoing, and the officer who fired the shots was placed on administrative leave, which is standard in such cases.
Police say the only other witness to the shooting was the grandmother of the deceased man, who was also the one who placed the 911 calls.