Minneapolis, MN- Minneapolis (WCCO) Two separate incidents of carbon monoxide poisoning sent 12 people to the hospital Monday afternoon.

Eight employees of Western Roofing Supply felt dizzy just before 2 p.m. They called 911 and were taken to Hennepin County Medical Center for evaluation.

Two of them needed oxygen immediately, but they were expected to recover.

Inspectors said they found high carbon monoxide levels near the furnace and the warehouse.

Four employees of an Eden Prairie store were also sickened Monday by carbon monoxide.

The Eden Prairie Fire Department responded to the Party America store at approximately 2:30 Monday afternoon.

Investigators found unsafe carbon monoxide levels inside the building. Employees had reported feeling sick and a pregnant woman and a manager had already gone home.

They were all taken to a hospital and were expected to recover.

Fire investigators said they believed the carbon monoxide built up when the floors were cleaned overnight. They reported a lack of proper ventilation in the store.