It’s still unclear what sparked a downtown fire in the southeast Iowa town of Fairfield. An investigator with the State Fire Marshal’s Office will be on hand in Fairfield to try and determine what caused the building on the east side of the town square to go up in flames on Thursday. The initial call came in at 3:46 a.m., but crews remained on scene for well over 12 hours. An occupant of the upper level jumped out a window to the alley below as the fire was breaking out. The man was treated and released at Jefferson County Hospital. This is the second downtown fire Fairfield has seen in the past year. In June, another building on the south side of the square was destroyed in a blaze which took millions of gallons of water to extinguish. It, too, was undergoing renovations that were nearly complete.