Investigators are trying to figure out what caused a fire at an abandoned building on the city's South Side, fire officials said Thursday. The fire was reported just before 11 p.m. Wednesday at the abandoned Sunshine Lodge nursing home, found in the 2700 block of Pleasanton Road near Southwest Military Drive. Officials said firefighters battled the flames for more than two hours. At this time it is not known how much damage was caused to the building by the fire. Arson has been called in to investigate the cause. The investigation is ongoing.