EMPLOYEE WAS BOLTING TOP IN NO.2 ENTRY & A PIECE OF DRAW ROCK FELL BETWEEN THE 1ST & 2ND ROW OF BOLTS WHICH HAD BEEN INSTALLED. ROCK HIT EE IN THE LOWER LEFT SIDE OF BACK. COMPLAINT OF PAIN IN LOWER BACK, LEFT HIP AND LEFT LEG. TRANSPORTED TO HOSPITAL, RELEASED AFTER X-RAYS.