Tucson Fire units responded to the 400 block of East Congress Street at 5:41 a.m. Sunday after multiple 911 calls reporting smoke and fire coming from a building. Engine 1 arrived on scene and encountered heavy fire and smoke coming from the structure. Fire crews pulled hose lines and worked to locate and contain the fire. Remaining support units performed water supply to the Engine Company and building sprinkler system, utility control, and RIC (rapid intervention crew) duties. The fire was found in an exterior stairwell with infiltration into the interior of the structure and was extinguished and called under control 14 minutes after the first unit arrived at 6:10 a.m. There were no reports of injuries to firefighters.