Firefighters knock down raging 4-alarm fire at Medford auto shop

Smoke was seen at the scene in Medford. Abigail Feldman for the Boston Globe

MEDFORD — A four-alarm fire roared through a Medford auto repair shop Wednesday, shutting down Mystic Avenue as thick black smoke flooded the streets.

The fire broke out at Automotive Services of Boston around 9:30 a.m., Somerville Fire Inspector Earl Johnson III said at the scene.

One firefighter was taken to Massachusetts General Hospital with injuries that were not life-threatening, Medford Fire Lieutenant William Young told the media. The building was evacuated at the start of the fire, and no other injuries were reported.

Young said firefighters were forced to go inside the building to put out the flames.

“We got reports that the roof was a bit spongy,” he said, which made it unsafe to fight the flames from the rubber roof. The roof had caved in by the end of the fire.

The fire was declared under control as of 1 p.m., Medford Fire Chief Frank Giliberti said. But firefighters on scene were still working to put out hot spots at 2 p.m. Young said it may take a few more hours to fully extinguish the fire.

Young said the power to all businesses within half a mile of the auto shop went out during the fire. A residence for people with special needs had to be evacuated because of the power loss, he said.

Johnson said Automotive Services is primarily a rim-cleaning shop, so the building contains a large quantity of cleaning solvents. Officials were able to prevent the fire from spreading to a neighboring business, Milhench Metro, a janitorial supply store that carries flammable chemicals and materials, Johnson said.

Somerville Fire Chief Matt Wall said smoke from the fire could be toxic because of materials in the auto body shop.

“It’s hard to say, but you always expect the worst,” he said.

Both sides of Mystic Avenue were closed to traffic. Firefighters struck a fourth alarm shortly after noon, a fire official said by phone.

In addition to firefighters from Somerville, firefighters from Everett, Chelsea, Boston, and Malden also responded to the scene to assist.

Medford Mayor Stephanie M. Burke said Automotive Services of Boston was in business for more than 20 years.

Young said officials were investigating the cause of the fire as electrical. State Police were on scene conducting an investigation Wednesday afternoon.