WATERVILLE — An epidemic of carbon monoxide poisoning swept the state Saturday as icebound Mainers trying to stay warm and fed fired up generators, space heaters, charcoal grills, camp stoves and other equipment in their homes.

A Waterville man who ran a generator in his basement became the ice storm’s first casualty when the deadly gas seeped upstairs to the second floor, where he and his wife were sleeping Friday night.

A 73-year-old Newport man whose wife found him at noon Saturday in the basement with the generator also died. Officials suspect carbon monoxide poisoning in that case as well.

“This is going to be lethal if we don’t get the word out, ” said Dr. David J. Stuchiner, medical director of the emergency department at Central Maine Medical Center in Lewiston.

At Stuchiner’s hospital, right in the heart of the storm’s worst damage, doctors treated 12 cases of carbon monoxide poisoning in less than 24 hours. That’s how many cases they normally see in two years.

At least four residents of the Ledgeview Estates nursing home in Cumberland were transported to Portland hospitals late Saturday night by rescue units from Cumberland and Freeport, officials said. Others were being monitored on the scene for signs of carbon monoxide poisoning. No other details were available.

At least 12 other people have suffered carbon monoxide poisoning since the storm began Thursday. With colder temperatures on the way, emergency officials worry that there might be more.

Martin McCluskey, 58, died Saturday after he and his wife Gladys, 66, ran a gas generator overnight in their Trafton Road home in Waterville, filling the building with odorless, colorless carbon monoxide gas.

Gladys McCluskey was listed in critical condition at St. Joseph’s Hospital in Bangor.

Other victims include a Belfast couple who barbecued food indoors on a charcoal grill and a Waterville man poisoned by a faulty kerosene heater.

Five others from Waterville, West Newfield and Skowhegan were exposed when they ran gas generators in their garages or basements.

A couple at 9 Belden St. in Portland were overcome Saturday afternoon by carbon monoxide fumes coming from a gas generator in their garage. Officials said the couple could not be identified immediately. They were being treated Saturday night at Maine Medical Center.

“You would never drive your car into a garage, close all the doors and windows and turn it on unless you wanted to kill yourself, ” Stuchiner said. “But putting a portable generator in your basement is like doing the same thing. People aren’t really thinking about that, I think.”

Carbon monoxide is produced by burning gas, kerosene, charcoal, wood and other fossil fuels. It suffocates people because it binds to blood cells better than oxygen.

Normally the oxygen breathed in through the lungs binds to the blood, which then takes it to tissues where it can be released and used by the body.

“What happens is the carbon monoxide takes its place and it won’t let go, ” Stuchiner explained. “It binds there and it won’t go away. So there’s no blood cells left that can take the oxygen to the tissues.”

The gas is fatal at high levels, while moderate levels cause fatigue, nausea, headache, dizziness or other flu-like symptoms.

Emergency officials urged residents Saturday not to run generators, gas grills, open-flame hibachis or similar devices indoors.

“All kinds of things go through your mind about how to keep warm, ” said Ray Poulin, assistant fire chief in Waterville. “We don’t want people bringing just anything into their house and lighting it.”

The McCluskeys, whose power was knocked out by the storm, presumably were using the generator inside to provide lights and heat, Poulin said.

Waterville police Sgt. Joseph Shepherd said the McCluskeys had opened the basement’s exterior bulkhead doors and closed the door leading upstairs.

But the carbon monoxide fumes still rose all the way to the second floor, where the couple was found in their bedroom, he said.

They were found unconscious at 8:20 a.m. by their son, Darrell Estabrook, said Shepherd. Martin McCluskey was declared dead at Maine General Hospital in Waterville.

His wife was treated and then transferred to St. Joseph’s in Bangor, one of two Maine hospitals with hyperbaric chambers, equipment used to treat carbon monoxide poisoning.

People with serious cases of carbon monoxide poisoning are placed in hyperbaric chambers and exposed to oxygen at high pressure.

The equipment, also used to treat deep-sea divers who suffer “the bends, ” drives carbon monoxide out of the bloodstream.

Sheryl Sparlin, nurse manager of hyperbaric medicine at St. Joseph’s, said Saturday the hospital had treated three people for carbon monoxide poisoning in the ice storm.

Two were Belfast residents who barbecued food on a charcoal grill inside their home, and the third was a Waterville resident poisoned by a faulty space heater, she said.

At Goodall Hospital in Sanford, which also has a chamber, five or six people had been treated since the storm began, said Dr. Albert Pollard.

“This happens every time we have a power outage, ” he said.

Pollard added that all the victims had been using gas generators indoors, in garages or basements.

He said those treated were from various towns, including Skowhegan, Waterville and West Newfield.

At Maine General Hospital’s unit in Augusta, a nursing supervisor said five people were admitted and then discharged after treatment for carbon monoxide exposure Thursday night.