Eight people are still unable to return to a Norwalk multifamily home that became filled with carbon monoxide over the weekend.

Fire officials say a malfunctioning furnace filled the building with carbon monoxide Saturday night. 

Firefighters say they were able to rescue two people who were found unconscious inside the Woodward Avenue home at around 8:30 p.m. They say if the call had come in any later Saturday night, the residents may not have made it out alive. 

Fire officials say four others were sent to the hospital for carbon monoxide poisoning. 

City health officials are urging residents to make sure they have working detectors because carbon monoxide is clear, odorless and almost undetectable without one.