Arson is believed to be the cause of the latest fire, which ignited Monday night.

“We believe it was intentionally set,” Fire Chief Steve Hergenreter said.

The fire was reported at 10:33 p.m.in the former school at 416 S. 10th St.

When firefighters arrived, flames were blasting out of some third floor windows on the south side of the building.

-Messenger photo by Bill Shea
Fort Dodge firefighters climb the aerial ladder to attack a fire burning in the third floor of the former Fair Oaks Middle School, 416 S. 10th St., Monday night.

Firefighters initially used large caliber nozzles mounted on a pumper truck and at the tip of the aerial ladder to extinguish most of the fire. Then they dragged hose up the aerial and in through windows to finish the job.

Large diameter hoselines were connected to a hydrant on the school property and at Fifth Avenue South and 12th Street to supply the needed water. Fifth Avenue South west of 12th Street and the Kenyon Road Bridge were closed to traffic.

Hergenreter said about 3,000 square feet of space on the third floor was gutted. He said the area contained a “significant fire load” because of large bookcases and wood framing.

No one was found in the building.

Firefighters were on scene until about 2:30 a.m. Tuesday.

-Messenger photo by Bill Shea
Flames blast out of a third floor window at the former Fair Oaks Middle School Monday night.

A fire on May 27 damaged another portion of the third floor and burned a hole through the roof.

The school building has been vacant since 2018. There had been some previous, smaller fires in it.

Both the Fair Oaks and Phillips middle schools closed in 2013 when the new Fort Dodge Middle School opened at 800 N. 32nd St., The following year, the buildings were sold to Foutch Brothers LLC, of Kansas City, Missouri, which announced plans to turn the schools into apartment buildings.

Foutch Brothers did convert the former Phillips Middle School at 1019 Fourth Ave. N., into apartments, but so far nothing has been done with the Fair Oaks building.

In 2015, after severe structural problems forced the closure of the old Duncombe Elementary School building at Sixth Avenue North and 16th Street, the developer allowed the Fort Dodge Community School District to move that school’s students and teachers into the Fair Oaks building. That arrangement ended with the opening of the new Duncombe Elementary School in 2018.

-Messenger photo by Bill Shea
A Fort Dodge firefighter pulls large diameter hose across Fifth Avenue South toward the former Fair Oaks Middle School during a blaze there Monday night. That hose was connected to a hydrant at Fifth Avenue South and 12th Street and carried water necessary to extinguish the fire.

Online records of the Webster County Assessor’s Office list the building’s current owner as Fair Oaks Homes LLC, of Johnston. Those records show it was built in 1931.