WINSLOW — A 79-year-old woman was critically burned over 40% of her body Saturday while trying to start a brush fire by using gasoline as an accelerant, according to a fire official.

The woman was taken by ambulance to Thayer Center for Health in Waterville after the 12:04 p.m. incident and then flown by LifeFlight of Maine to Maine Medical Center in Portland, Winslow Deputy Fire Chief Michael Murphy said.

“She’s in critical condition,” said Murphy, who helped treat her.

He said the woman, whom he declined to name, was in the backyard behind her house in the 900 block of Benton Avenue when she put gasoline on the brush pile to try to start it and she was burned.

Murphy and a paramedic from Fairfield and Benton Fire-Rescue Department treated her and took her to Thayer by Winslow ambulance, he said. He said they assisted LifeFlight with advanced medical care before she was flown to Portland.

The Office of State Fire Marshal is investigating the incident, he said.

Murphy cautioned against using gas or other such substances to start brush fires.

“She was trying to start a brush fire with gas,” he said. “Never use any accelerant to start a brush fire.”