LYNN, Mass. -- The Lynn Fire Department, which enforces state regulations on carbon monoxide detectors in the city's homes, found itself Saturday explaining why its own headquarters did not have detectors installed.

Two firefighters were hospitalized Friday after being overcome by carbon monoxide at the department headquarters on Western Avenue.

"It’s a little strange that it happened at that location," said City Council President Tim Phelan.

The problem was discovered after Ladder Company 2 returned from a call and found one firefighter acting groggy. A second firefighter was overcome by fumes when he pushed up a ceiling tile in a second floor office.

Fumes from a backup generator in the basement are blamed for causing the leak. The fumes collected near the building's roof.

"There was a vent that should not have been covered, but was covered and did not allow fumes to get out of building," said Phelan.

Carbon monoxide levels in the office were measured at 660 parts per million. NewsCenter 5's Lynn Jolicoeur reported that the fire department forces evacuations when levels reach 70 ppm.

One of the firefighters was taken to Massachusetts General Hospital in Boston and the other to Union Hospital in Lynn.

Phelan said he was surprised to learn that most of the fire houses in Lynn did not have CO detectors. The fire chief said detectors would be purchased and installed immediately.

One of the firefighters was treated and released. The second was taken to Boston for treatment in a hyperbaric chamber. His condition was not immediately released.