Officials with the state fire marshal’s office say a 39-year-old Sanford man was severely injured when a wood furnace exploded in his backyard. Authorities say Thomas Basinger was trying to ignite a fire in the furnace on his Lebanon Road property when it exploded Tuesday afternoon. Investigators say Basinger’s wife doused her husband with a garden hose, but he suffered burns on more than 90 percent of his body. He was taken to Massachusetts General Hospital in Boston for treatment. Officials believe Basinger used a flammable liquid in the furnace that exploded when he tried to light it. They are trying to determine exactly what happened.