Today we responded to a building fire mutual aid into Springfield at a country club. Upon arrival we were assigned to the third floor to open up and check for extension. While operating directly under the fire pulling the ceiling. After a few hits the entire ceiling came down on one of my members. He was knocked to the ground and out cold. We try a few times to call out and see if he was ok, with no response I was about to call the MAYDAY as he came to. He walked out and was transported to the local hospital, had a concussion and and headache. He was released and sent home.