SANGER, Calif. (KSEE/KGPE) – The Sanger Fire Department revealed the cause of an ammonia leak at Pitman Farms in Sanger Monday. At around 3 a.m. on Monday, fire crews were alerted to a potential hazardous materials incident involving anhydrous ammonia at Pitman Farms at 1489 K Street in Sanger.  Fire crews say when they arrived, employees from Pitman Farms had already been evacuated and emergency crews met with facility representatives to determine the extent of the ammonia leak. Fire officials say the ammonia was isolated in a large freezer room within the facility. It was determined that an accidental failure of a fan within the cooling unit inside the freezer failed, causing the ammonia release.  During the incident on Nov. 3, Sanger Fire said a mutual aid request was made for a level one hazardous materials team, and the Fresno Fire Department responded to assist in the mitigation efforts.  Due to the ammonia smell in the surrounding neighborhood, shelter-in-place advisement was issued for those in the immediate area. Emergency crews say they continued to make entry into the hazardous space, performed air monitoring of the affected and surrounding areas, and utilized ventilation techniques to keep the public safe while the ammonia dissipated.