Fond du Lac firefighters are investigating the cause of a fire at a smoke shop Thursday morning. At 7:39 a.m., Fond du Lac Fire Rescue responded to Big Jay’s Smoke Shop at 111 S. Main Street. Crews found smoke inside the three-story mixed use building. Fire was located on the first floor inside the smoke shop. People who live in apartments above the smoke shop escaped without harm. The fire caused “a moderate amount of damage inside and smoke damage throughout the building,” says Fire Chief Peter O’Leary. No one was in the business at the time of the fire. The American Red Cross is assisting the residents who were displaced.