At ~4:04 PM, Westmoreland 911 dispatched Station 20 (Murrysville VFC) for an Automatic Fire Alarm (AFA) at the Franklin Regional Middle School Station 20 responded with Truck 20 (3 firefighters), with Captain 20 going directly to the scene, and 6 additional firefighters on standby with Engine 20 at the station. Westmoreland 911 also dispatched the following additional stations to support Station 20: Export VFC (Station 22), White Valley VFC (Station 64), Sardis VFC (Station 78), Station 236 (Holiday Park VFC), and Station 170 (Monroeville #4). Captain 20 was first on scene, established the command, and found that the school had been evacuated. Engine 22, Truck 20, Engine 78, and Engine 64 arrived on scene. Upon investigation it was found that a HVAC Unit was leaking coolant, which set off a detector. The issue was turned over to the school's maintenance department, and Command 20 returned all on -scene and enroute units. Truck 20 returned to service and station.