A large electrical transformer is on fire in the 8200 block of Eastern Boulevard at the Back River Waste Water Treatment Plant.
Firefighters responded to the scene, and foam trucks have been requested, according to Cpl. Cathy Batton, a spokeswoman with Baltimore County Public Safety.
Heavy black smoke is visible in the area, according to online commenters.
The fire started at about 2:30 p.m., according to Patch readers who sent in tips about the blaze.
The Baltimore County Fire Department had about 16 pieces of equipment and 40 firefighters and other personnel on the scene, according to Batton.
One firefighter was taken to Johns Hopkins Bayview Medical Center with symptoms of heat exhaustion, according to a WBAL-TV report.