The state’s top fire investigator typically sees six to a dozen fires a week that require the services of his office, but 23 were reported about two weeks ago. And most of them, State Fire Marshal Joe Thomas said, should never have happened.

Thomas attributed almost all of the fires to two causes: poorly-maintained alternative heating sources that broke down or a lack of working fire-safety devices, such as smoke detectors.

“It’s one thing to have a mechanical failure, like a short circuit or something like that, but the vast majority of fires we are seeing have some type of human element attached to them,” Thomas said Friday. “They didn’t have to happen.”

“A wood stove was the most common source,” Thomas added. “Usually the worst combination is a wood stove with a malfunctioning chimney, or a wood stove that isn’t even adequately in shape for burning wood or is too close to something that will burn.”

The 23 fires reported the week of Jan. 21, plus nine more reported the following week, included blazes in Augusta, Bethel, Casco, Harrington, Lebanon, Somerville, Stockton Springs, Sullivan, Trenton, Waterville, Wells, and Yarmouth, Thomas said.

Of the 32, four have been logged as being of suspicious origin, Thomas said. He said he didn’t know whether 23 fires in a single week was a record-setter for Maine.

Smoking materials and a lack of smoke detectors caused a double fatality in Easton on Jan. 29, fire officials said.

Heavy fire damage to a house in Somerville on Jan. 24, in which a 92-year-old man died, will likely leave investigators unable to prove what ignited the flames. Another fire that day, which destroyed a 150-year-old Bangor home, apparently started in a chimney, officials said.

The sudden surge in fires has left Thomas’ 13-member staff of inspectors and investigators scrambling. The preventable nature of the fires is frustrating to contemplate, Thomas said.

“You want to stand up and scream ‘Pay attention!’ There is information out there. We make everything as informative as we can about safe appliances and everything else. People need to pay attention and heed that word. The information is out there for a reason.”

Winter fires are also especially miserable for firefighters, who have to battle climate conditions in addition to the flames. In Millinocket, firefighters trying to extinguish a blaze that destroyed a Medway Road house in early January had to surmount big piles of snow, icy conditions and water runoff that created icy that two firefighters slipped on, all caused by a woodstove left burning.

Thomas recommends that homeowners and landlords ensure that chimneys are inspected and cleaned regularly; smoke detectors have fresh batteries and are placed in well-trafficked areas; and any heat source has at least three feet of clearance around it.

Homeowners and renters should also have clearly outlined escape plans from their dwellings and keep those exits free of snow and ice, Thomas said.

Anyone with fire safety questions is encouraged to call their local fire department or the fire marshal’s office at 626-3870.

The fire marshal’s office investigated 650 fires in 2012, including 164 confirmed arsons and 19 fatalities. In 2011, 604 fires, 22 fatalities and 179 arsons were investigated, while in 2010, 546 fires, 9 fatalities and 157 arsons were investigated, Thomas said.