Firefighters believe a gasoline-powered generator being used to provide electricity to a home likely sickened five people in Waterloo late Wednesday night (March 2, 2016).

According to Waterloo Fire Rescue officials, four adults and a toddler were sent to the hospital to be treated for symptoms of carbon monoxide poisoning.

Battalion Chief Marty Freshwater said when firefighters arrived at the home in the 500 block of Archer Ave. around 11 p.m., they found a woman unconscious in a doorway. The other residents were outside the house and conscious, but all of them were feeling ill.

According to fire officials, the residents were apparently overcome by the colorless, odorless and poisonous gas about 30 minutes after starting a generator inside the home's laundry room.