The West Fargo Fire Departments responds to a possible carbon monoxide call at the Sanford West Fargo Clinic around 10 a.m.
Employees of the clinic said they felt sick and thought there might be a carbon monoxide leak in the building.
Fire officials say there is no sign of CO in the building but the employees were taken to the emergency room to be treated.
The fire department recommends all buildings with a gas furnace to have carbon monoxide detectors.
The clinic does not have one.
"We had a couple people feeling ill, they went to the ER, we took our monitors out checked the area out, we found nothing. FM Ambulance were on scene also and found nothing," said Fire Marshal Dell Sprecher.
The signs of being exposed to carbon monoxide are similar to the flu and include feeling nauseous and having a headache.