OMAHA, Neb. -- Investigators say a car that was left running inside a garage led to the carbon monoxide deaths of three Omaha residents last week. 

The Omaha Fire Department confirmed Wednesday that the car was the source of the colorless, odorless gas that killed 52-year-old David Coleman, 18-year-old Thomas Coleman, and 19-year-old Cole Oban inside a west Omaha home. 

Their bodies were found last Wednesday. 

A fourth person was taken to a hospital for treatment. 

Investigators believe the fatal carbon monoxide poisoning was accidental.