Firefighters arriving at the residence shortly after 8:30 p.m. Monday found a 55-gallon drum in the basement that was filled with smoldering charcoal briquettes.
Hackensack Deputy Fire Chief Matt Wagner said the building's residents were treated outside before being taken to local hospitals.
Wagner said the carbon monoxide exposure wasn't believed to be life-threatening.
The building did not have working carbon monoxide detectors.
Wagner said a barbecue pit needs proper ventilation, and is best left outside.
Information from: The Record of Bergen County, http://www.northjersey.com