BOSTON (WHDH) - Eleven firefighters and one resident were hospitalized after a Level 3 hazmat situation prompted the evacuation of a five-story rooming house in Boston’s South End on Friday, officials said.

Firefighters responding to 1740 Washington Street around 12:15 p.m. on Friday ordered all residents out the building due to noxious fumes on the third floor, according to the Boston Fire Department.

An investigation determined that the fumes were coming from a mixture of cleaning supplies, Deputy Fire Chief Robert Calobrisi later told reporters.

“It was determined that it was a combination of bleach and Murphy’s Oil Soap, which makes sodium hypochlorite gas, chlorine gas,” he said.

Everyone who was transported from the scene underwent precautionary treatment.

“All were very minor,” Calobrisi said of the injuries. “Mostly just evaluations, obviously, with the potential exposure and the heat today.”

The building has since been ventilated.

Calobrisi says there were “zero readings” on meters being used by firefighters following the evacuation.

Residents have been allowed back inside.

This is a developing news story; stay with 7News for updates online and on-air.

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