The Norwalk Fire Department says several people were sent to the hospital after carbon monoxide filled a multi-family home in South Norwalk.

Officials say a boiler malfunctioned, causing carbon monoxide to fill the home located at 35 Woodward Ave. at around 8:30 p.m. Saturday.

Fire officials say eight residents live in the house, and six of those residents were rushed to the hospital with carbon monoxide poisoning.

They are all expected to be OK.

Capt. Mark Franzen, of the Norwalk Fire Department, said when they arrived at the building, they found two of the victims unconscious. He said that another victim, who was reluctant to leave, had to be rescued.

Franzen said when they used the meter to check carbon monoxide levels, it "pinged out at about 1000 parts per million, which is extremely hazardous."

Officials are investigating what caused the boiler to malfunction and whether carbon monoxide detectors were installed.

They recommend cleaning boilers every year to prevent flues from clogging with soot, and to ensure the fire is burning hot enough.