Six family members from Middle Island were treated at a hospital Wednesday morning for carbon monoxide poisoning after using a generator in their basement during a power outage, officials said.

Four of the six taken to John T. Mather Memorial Hospital in Port Jefferson were treated in a hyperbaric oxygen unit, said spokesman Stuart Vincent.

The family was alerted to the problem when one member, a woman, woke up with a headache, Vincent said, and determined it must have been caused by the generator.

Suffolk County police said they got a 911 call at 5:04 a.m. from the Artist Drive residence requesting assistance for possible carbon monoxide sickness.

Three chiefs, two engines and two ambulances from the Middle Island Fire Department also responded, as well as an ambulance from Coram, said First Chief William Nevin, who was on the scene.

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The six people were taken in noncritical condition, with symptoms including headaches and nausea, he said.

The basement registered “very dangerous” levels of carbon monoxide, Nevin said, adding that “thank God” no one was in the basement, as the outcome could have been much worse.

Generators should always be kept outside a home, far enough away so exhaust won’t be pushed into the residence, he said.

“They should never be inside” or even in an attached garage, he said of generators.

Carbon monoxide is an odorless, colorless gas that can cause sudden illness and death. The Centers for Disease Control and Prevention estimates that each year in the United States, more than 400 people die from carbon monoxide poisoning and 20,000 are sent to emergency rooms.