Dawsonville City Hall was closed for a period of time Monday morning due to a dangerous gas leak.

I came in to work late Saturday afternoon and thought I had smelled gas then, said Mayor James Grogan. But then I didnt smell it after a while, so I didnt think anything of it.

When city employees went in to work on Jan. 7, the odor of gas was obvious. They immediately evacuated the building and contacted Dawson County Emergency Services.

Our monitors detected a gas level that was about 30 percent of the lower explosive limit of natural gas on the second floor in the council chambers, said Capt. Jason Dooley with DCEMS. Dooley explained that the levels would have to be at 100 percent in order to ignite, but the gas levels should not reach over 10 percent.

Anything over 10 percent is pretty dangerous, he said. But they had already evacuated the building.

Emergency workers found that a rooftop heating/air-conditioning unit was malfunctioning, causing the gas leak. We shut the power and gas off to that, Dooley said, then ventilated the building.

Grogan said the cause of the gas leak was undetermined, but a heater did have repairs made to it the previous Friday, Jan. 4. Atlanta Gas Light sent a representative to City Hall to look at the unit.

In the meantime, City Hall was closed for approximately an hour while emergency workers shut off the gas and ventilated the building. Grogan had initially thought that the scheduled 5 p.m. City Council meeting might be canceled, but it continued as normal.