A smoke alarm went off at the Great Falls Engineers House just before 3 a.m. on Tuesday morning, alerting the local fire department. The Montgomery County Fire Department responded with numerous vehicles. The fire started in an unused electrical outlet and spread to nearby boxes of paper, but was contained to a single wall in a lower room. Park personnel conducted a preliminary assessment of the damage yesterday and secured the building. The Engineers House is located within C&O Canal near Great Falls. The house was built in 1874-1875 to serve as a residence for the gatekeeper in charge of the Washington Aqueduct. In recent years, the Engineers House has been used for administrative purposes.