PITTSBURGH (WPXI) – A warehouse that once housed nightclubs in Pittsburgh’s Strip District caught fire Monday morning. Fire officials are calling the fire suspicious as they are still working investigating the cause. The fire was reported just after 4:30 a.m. at the four-story warehouse, which has been under construction at the intersection of Smallman and 16th streets. The building is being converted to office, retail and restaurant space. At one point, electrical wires caught fire, officials said. Pittsburgh Public Safety Director Wendell Hissrich said because the building is under construction, there were specific dangers for fire crews. “There was heavy fire on the Smallman Street side. There’s many hazards. The building is currently under construction. Floors were missing. There are different various cylinders throughout the building and, of course, we have concerns with electricity and gas throughout the building,” Hissrich said. Heavy smoke was seen coming from the building before firefighters brought the fire under control. Drivers were asked to avoid Smallman Street, Penn Avenue and Liberty Avenue between 11th and 21st streets. Liberty and Penn avenues have since reopened.