A Fairfield family of six was rushed to the hospital after being overcome by what firefighters said were "near-fatal" levels of carbon monoxide from a gasoline-powered generator that built up inside their home early Monday.

Firefighters were dispatched early Monday to a two-family home on Beaconview Drive about 1:30 Monday to investigate the report of an unconscious man. On arrival at the house, firefighters found two adult males, an adult female and two children ages 13 and 9 on the front lawn, suffering from what appeared to be carbon-monoxide poisoning. Another woman was found unresponsive inside the house during a search by Firefighters Jay Swindon and Jason Charney.

Firefighters' tests confirmed the home was filled with dangerously high levels of carbon monoxide -- an odorless, colorless but potentially lethal gas -- and identified the source as a gasoline-fueled portable generator operating within the confines of the home's basement.

The generator had been activated by the family after Tropical Storm Irene knocked out power to thousands in town Sunday.

AMR Ambulance paramedics and firefighters began emergency medical treatment, and additional fire units were called to the scene to ventilate the house.

After emergency resuscitation at the scene, the family of six was rushed for specialized medical treatment to Norwalk Hospital, which has a hyperbaric chamber. Condition of the various family members was not immediately available later Monday morning.

Assistant Fire Chief George Gomola, the incident commander, said in a statement later that gasoline- or propane-fueled appliances should never be used indoors because they generate carbon monoxide, which can build up to deadly levels in a confined space.

Symptoms of carbon-monoxide poisoning include headache, nausea and vomiting.