VIDEO: Investigators are looking into what sparked a three-alarm fire in Salt Lake City overnight. Firefighters were called to the fire at a building near 300 W. and 1500 S. just before 2 a.m. No one was in the building at the time of the fire. "There was a short moment where we were especially careful to make sure other structures weren't threatened because this is a business district and things are pretty close together," SLC Fire's Audra Sorensen said. "That's why we called in a third alarm fire and that's always an extra precaution that we take to make sure that our crews are safe and that other buildings are protected from any fire spreading."