South Charleston, WV – No one was hurt after dangerous levels of carbon monoxide were discovered inside a post office.

Firefighters tell WSAZ.com they responded early enough that everyone evacuated the building before someone was hurt. Several people were checked out by medics as a precaution.

It was reported about 8 a.m. Saturday at the United States Post Office on 4th Avenue and D Street in South Charleston.

Brenda Burket comes to the South Charleston Post Office every day, but Saturday the trip felt a lot different.

Burket and her sister arrived just hours after a dangerous gas leak caused the building to be evacuated.

“It scared us,” she said. “This is the last place you would have thought to get sick.”

Employees say they smelled a strong odor of sulfur shortly after 7 a.m. and called for help.

Investigators identified the problem as a carbon monoxide leak and traced it to a fork lift in the warehouse.

They say a battery charger to the equipment malfunctioned, emitting the gas.

“Anybody exposed to that level or an extended period of time would start feeling sick and have flu-like symptoms,” said VIrgil White, South Charleston assistant fire chief.

Crews say it took two hours to ventilate the building and left the doors open as a precaution.

No one was injured during the leak. Employees were evaluated by medics in the parking lot.

Officials say the building will continue to be monitored throughout the weekend.