From staff reports Portland firefighters quickly extinguished a fire in a Congress Street apartment building Monday afternoon. The fire was reported shortly before 3 p.m. in a nine-unit building at 871-873 Congress St. Smoke detectors activated and the residents had left the building when firefighters arrived, said Deputy Fire Chief Shawn Neat. Firefighters used an aerial ladder to spray water on the rear of the building while crews launched an interior attack that quickly extinguished the blaze, he said. The fire damaged the rear wall of a second-floor apartment and that apartment cannot be inhabited until repairs are made, he said. The cause of the fire remains under investigation.