Nate Stritzinger says the incident happened about 1:30 a.m. Sunday at Nate's Bar and Grill in Cochranton, about 75 miles north of Pittsburgh.
Stritzinger says the suspect put a money bag on the bar after firing one shot into the ceiling. He fired a second shot over the head of his bar manager after she told the robber, "We don't do that here," when he demanded money.
That's when Stritzinger says his customer grabbed the gun and chased away the robber.
State police in Meadville are still trying to identify the man who also fired a shot into the ceiling while robbing another bar just past closing time on Saturday in Saegertown.