At 21:15 units were alerted to the reported building fire at Chalk Point Power Plant in Aquasco MD. While units were in route is was determined to be a fire at the guard house. Due to the guard house being about 10' by 10' the Chief officers from station 36 reduced the assignment to 2 engines, 2 trucks, and 2 tankers. Engine-Tanker 36 arrived to find a heater malfunction and placed the balance of the assignment in service.