DCFD responded to the Dunn's Corners Elementary School late this afternoon for a report of smoke filling the school. Upon arrival, a light smoke condition was found in the area of the library. As evacuations were swiftly conducted, firefighters investigated potential causes. After a thorough investigation, it was found that the rooftop hvac had malfunctioned and caused a small fire within the unit. Firefighters isolated the power and vented the smoke. The scene was turned over to school officials and students were allowed to reoccupy the school within 15 minutes.