SEATTLE -- The death toll rose to 12 Monday from a storm that knocked out power to more than a million homes and businesses, with health officials warning of a "carbon monoxide epidemic" from indoor use of generators and charcoal grills.

Four more people were found dead Monday from apparent carbon monoxide poisoning.

Chief Russ Pritchard of the North Highline Fire District said the four were found in a home near the White Center neighborhood south of Seattle, along with a fifth person who was taken to a hospital in critical condition. The victims had been running a generator indoors.

Video: Family Killed By Carbon Monoxide Poisoning

Carbon monoxide was also responsible for killing two men over the weekend.

Carbon monoxide poisoning has been a major problem in Western Washington, as people who lost power in last week's windstorm have been taking generators or other heating devices into their homes, unaware that they emit the colorless, odorless gas.

Gov. Chris Gregoire's office is estimating that more than 1,000 people have been seen at hospital emergency rooms with symptoms of carbon monoxide poisoning since the storm four days ago.

A 31-year-old man was found Sunday morning near a charcoal grill he was using to warm the bedroom of his home in Renton, and a 26-year-old man was found Saturday in the bedroom of his house in Kirkland, with a portable generator in a nearby room.

Falling trees, rushing water, burning candles and downed powerlines caused six of the deaths

At least 100 people have developed symptoms of exposure to carbon monoxide since the winds subsided Friday morning, including at least five admitted to Harborview Medical Center and more than 55 who have been treated in a hyperbaric chamber that re-oxygenates the blood at Virginia Mason Medical Center, officials said.

"We're dealing with a carbon-monoxide epidemic in Western Washington," said Dr. Neil B. Hampson at Virginia Mason's Center for Hyperbaric Medicine. "This has the potential to be the worst case of carbon monoxide poisoning in the country."

Gov. Chris Gregoire has declared a statewide disaster, freeing counties to spend money necessary to help victims of the storm that hit late Thursday and early Friday, and the state National Guard has been mobilized to help get fuel and supplies to hard-hit areas.

Approximately 170,000 Puget Sound Energy customers and 16,000 Seattle City Light customers remained without power Monday evening, primarily in east and southeast King County. Officials said it could be several more days before power is restored to all of them.

Also in the dark were 7,500 customers in the Snohomish County Public Utility District, 8,000 served by Peninsula Light Co. of Gig Harbor, 2,700 in Tacoma and more than 1,000 in the Grays Harbor County PUD on the coast.

Some 5,000 King County residents were still without telephone service.

One of the hardest hit areas was Woodinville where trees have fallen over a tangle of power lines and the local Top Foods grocery store has already lost more than $200,000 worth of food from lack of power. Video: Woodinville Residents Still Without Power

Four people died when the storm hit on Thursday, packing winds that gusted to about 70 mph in the Seattle area. One woman was trapped by suddenly rising water in the basement of her house in Seattle, and three people were hit by falling trees, two in vehicles south of Tacoma and one in a trailer park in McCleary.

A 48-year-old man died Saturday in a fire started by a candle burning in his home in Spanaway. And on Sunday, a man and his dog died they stepped on a power line while out for a walk in Gig Harbor, Pierce County sheriff's Detective Ed Troyer said. Troyer said neighbors had been clearing debris near the power line for days, unaware that it was live.

With temperatures in the low to mid-20s over most of the affected area early Monday, some retailers were running out of fire logs and batteries. Firewood was also in short supply, and there were still long lines at some gasoline stations as some motorists complained of sudden price increases at the pump.

About 100 King County residents stayed in emergency shelters overnight, and hundreds more dropped in for a hot shower or cup of coffee, the county's emergency management office said in a news release.

Katy Freiberg of Bellevue told The Seattle Times she and her children, ages 9, 8 and 3, went to an emergency shelter at North Bellevue Community Center to get showers, clean clothes and a warm meal Sunday after three days of relying on an outdoor barbecue grill for cooking and warmth.

"We were putting wood in the grill to cook and stay warm. We were basically living outside," Freiberg said. "We woke up this morning and it was so very cold, I said, 'Kids, we just can't do this anymore. We need to get warm."'

Avista Utilities, which serves the Spokane area, said Monday that about 200 customers in Spokane and Colville were without power, down from about 3,300 Sunday. Spokeswoman Debbie Simock said crews were expecting to have all service restored by Monday night.

By several measures the devastation exceeded that of the windstorm on Jan. 20, 1993, which left five people dead, at least 79 homes destroyed and about $130 million in damage.

Damages from the current storm have yet to be assessed, but the death toll this time is higher and the impact on the power grid appears to be more severe. Seattle City Light was reconnecting 175,000 buildings, compared with 110,000 in the 1993 storm, and Puget Sound Energy reported more damage to major transmission lines.