An electrical box is suspected of starting a fire that severely damaged a city owned house on the corner of Hoffman Road and Victory Drive on Sunday. Firefighters responded at 8:54 a.m. after a passerby reported flames at 2021 Hoffman Road. The occupants of the home firefighters arrived, said Mankato Department of Public Safety Fire Cmdr. Don Lehne. Firefighters found fire on the exterior of the south side of the building with flames spreading into the interior. The fire reached all three levels of the home before it was extinguished. Damages are estimated at $160,000. A malfunction of the electrical box on the exterior of the home is believed to be the source of the fire, Lehne said.