Fort Dodge firefighters are battling a fire at the former Fair Oaks Middle School — again.

A structure fire was reported shortly before 11 p.m. Monday at the building at 415 S. 10th St. Arriving on scene, firefighters found the third floor engulfed in flames.

Heavy fire could also be seen coming out of the windows on the south side of the building Monday night.

Fifth Avenue South is currently closed between South Eighth and South 12th streets.

Firefighters last responded to a fire at the vacant building on Memorial Day.

At the time, Fire Chief Steve Hergenreter said “human action” caused the May 27 fire.