Keene, NH – As the sun set in Keene on Saturday, firefighters were going door to door to every Liberty Utilities customer to check for carbon monoxide poisoning.

The city has 1,200 Liberty Utilities customers, Keene Fire Chief Mark Howard said.

As of Saturday night, the fire department had received more than 80 calls for the smell of gas. It is not, however, a gas leak, Howard said, but high amounts of carbon monoxide in the city’s gas.

Three people experiencing carbon monoxide poisoning had been hospitalized as of Saturday, Howard said. “It’s an odorless, colorless gas, carbon monoxide, referred to as a silent killer. It can be lethal if exposed to over time.”

Symptoms of carbon monoxide poisoning are, lightheadedness, dizziness or confusion, Howard said.

The gas emergency started with a power outage around 9 a.m., said Michael Licata, Liberty Utilities director of government and community relations. “We’re not positive the outage caused the issue. We’re still investigating,” he said Saturday afternoon, “What we are sure of is at some point, the blower that mixed air into the propane tripped and was no longer blending air with the mixture.”

That caused ineffective combustion, he said.

Later Saturday, Liberty Utilities spokesman John Shore said “the issue that caused the problem at the plant has been resolved.”

The alteration in the mixture of propane and air meant the fuel carried more energy, he said. Because a furnace or appliance may not completely burn the fuel with the different propane-air ratio, that appliance or furnace may release carbon monoxide into a building, Shore said.

Shore didn’t know how many downtown businesses were affected or how much money merchants might have lost in Christmas shopping sales.

Asked about assisting customers who lost sales, Shore said: “I know we’ll do right by the customers. That’s something that will have to be examined.”

As of 5 p.m. Saturday, fire crews from Keene and the area, in conjunction with Liberty Utilities personnel, were 15 percent through their inspection of 1,250 gas company customers, Howard said.

A group of Swanzey firefighters said they had already interrupted several Christmas parties and had just checked on a home where the family had been cooking a roast in their gas oven all day with no issues.

The gas emergency encompassed a 2-square-mile area out from Main Street, causing several downtown business to close, including restaurants.

Many people who had come downtown to enjoy lunch and then go Christmas shopping wandered downtown confused by the closures.

One shopper said every time she left a downtown store it had to be evacuated. Businesses that were open couldn’t use their gas, including stoves and heat.

Howard said an emergency shelter was opened at the city recreation center on Washington Street for Liberty Utilities customers without heat.