E-11, R-11, Chief 2 Responded to the Conestoga Golf Club for a water flow alarm. Arrived to find audible and visual alarms and employees evacuated from building. Staff advises they have had a fire. Found an exterior storage rack under a covered patio near kitchen area that had burned boxes and other material on it. Fire completely extinguished by automatic sprinkler system which was still flowing water. Flow of water stopped and system returned to service other than the single head that activated and put the fire out. Minor scorching to building but no structural damage. Fire determined to be accidental in nature.