CHESTER, S.C. -- Employees at Rauch Industries in Chester County closed the garage doors of their warehouse and ran forklifts inside the building, unknowingly exposing themselves to deadly fumes.

Chester firefighters said it could have been a fatal situation.

Rauch Industries packages and ships Christmas ornaments and Halloween items.

Officials said the business recently purchased a new air conditioning unit for the building. And because of the heat, employees shut the garage doors to cool the warehouse off.

Firefighters said without ventilation for the forklifts workers started passing out, vomiting, and suffering from severe headaches.

Fire Capt. Scott Inman said a safe level of carbon monoxide is 50 parts per million, but firefighters got a reading inside the building of 300 parts per million.

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VIDEO: 10 Employees Suffer From Carbon Monoxide Poisoning

"I think I counted about eight forklifts. They were moving the pallets around. That combined with the weather, they were closed up with air conditioning. Carbon monoxide just got the best of them," said Inman.

Firefighters evacuated the building for about an hour before sending everyone home for the day.