The Forsyth County Fire Department responded to three fires at two schools on consecutive nights this weekend.

Firefighters were dispatched to the first incident at North Forsyth High School at 9:04 a.m. Friday after they received reports of a fire, said Jeff Hundley, Forsyth County fire investigator.

The fire was intentionally set, said Hundley, although he could not provide other details given the exact cause is still under investigation.

Saturday, an engine was dispatched to Vickery Creek Middle School around 9:45 p.m. after a fire alarm sounded, according to Division Chief Jason Shivers, the department’s spokesman.

Once on scene, firefighters found smoke billowing from the school’s gym and called for backup, he said.

Four engine companies, two ladder trucks, two battalion chiefs, an investigator and an ambulance responded, per protocol, Shivers added.

Investigators later determined the fire was accidental and caused by the spontaneous combustion of a pile of oily rags on the gym floor.

Contractors are refurbishing the gym and appeared to have left the rags over the weekend, Shivers said.

“This is a great example of a careless piling of rags,” he said.

Shivers added that spontaneous combustion “is real” and investigators are confident no foul play was involved.

The third fire, which occurred around 11 p.m. Sunday, was directly related to the gym fire and also appears to be accidental, Shivers said.

A single engine responded to a report of a Dumpster fire about 25-30 feet from Vickery Creek’s gym, he added.

The Dumpster had been brought in by a remediation company hired to dispose of ceiling tiles, gym floor and other items damaged in the previous night’s fire.

While it is unclear whether hot embers from the debris ignited or another case of spontaneous combustion occurred, after reviewing video footage, investigators determined the Dumpster fire was also accidental, according to Shivers.

No one was injured in either of the fires, but the gym was damaged by both smoke and water, Shivers said. Smoke damage extended to the halls around the gym.