Crews spent hours fighting a fire inside a dilapidated commercial building Monday night. One firefighter was treated for heat and exhaustion but is expected to recover, said Battalion Chief Michael Moore with Waterloo Fire Rescue. Passersby spotted smoke coming from the building at 105 E. 10 St. around 8:50 p.m. Monday, and firefighters had difficult time pinpointing the location of the blaze inside, Moore said. He said dense smoke and the structure’s layout complicated efforts to reach the fire, and hazards such as crumbling walls and floors and deep elevator shafts made battle risky.