Valley Regional Fire Authority units responded to a commercial structure fire at 1802 M St. N.W. in Auburn at 6:12 a.m. today to find light smoke coming from an interior office. Firefighters noted that the sprinkler system had activated and water was flowing. Firefighters put out the fire quickly, limiting heat and water damage to the office where the fire had started then ventilated the warehouse and secured the sprinkler system. No firefighters were injured, but one civilian was treated at the scene for minor smoke inhalation. South King County Fire Investigation Task Force is investigating the cause of the fire.