The fire may have broken out in the boys' locker room, officials said.
MILLBURN -- Firefighters responded to a small fire at Millburn High School, officials said Monday morning.
The fire "started in a locked closet near the boys bathroom, it appears from a cardboard box near a light fixture," Millburn Police Capt. Michael Mulligan said.
The fire appeared to be small, with no visible damage outside the school.
There were no injuries as a result of the fire, and everyone was allowed back inside the school, Mulligan said. Students and teams were seen using the facilities and nearby athletic fields later Monday morning.
It is unclear whether or not the fire caused any damage to the locker room.
A school spokeswoman did not immediately respond to a request for comment.
Jessica Mazzola may be reached at jmazzola@njadvancemedia.com. Follow her on Twitter @JessMazzola. Find NJ.com on Facebook.