Mystic — A house fire injured two residents Thursday night, including an elderly woman who was trapped in the burning home and suffered life-threatening injuries.

The fire at 97 Somersett Drive, on the Groton side of Mystic, initially was called in at 6:43 p.m., Mystic Fire Department acting Chief Anthony Manfredi Jr. said. It was elevated to a first-alarm fire at 7:03 p.m.

The elderly woman was located inside the home and was unconscious and not responding when she was removed. CPR was started, Manfredi said, and the woman was taken to Lawrence + Memorial Hospital, where the plan was to have a Life Star helicopter transport her to the Connecticut Burn Center at Bridgeport Hospital. Manfredi didn't know her condition but shortly after 9 p.m., he said that people were trying to stabilize her first.

Groton Town police said in a 10:50 p.m. news release that her injuries were "with life-threatening injuries." The woman later died, police said Friday.

The second victim — the woman's son — was transported to the hospital with minor injuries, Manfredi said.

He said there were four 911 calls about the fire, which began in a second-floor bedroom at the front of the house. Flames were leaping out of one window when fire crews arrived, he said, and the blaze took 30-35 minutes to knock down.

The fire extended into the attic and the rear bedroom, Manfredi said, but the majority of the damage was contained to the front left corner of the house. One second-floor window was completely blown out of the two-and-a-half-story home and burned wood frame was visible on the left side of the triangular structure.

Julie Smith, who lives a few houses down, was one of multiple people to call 911 about the fire. She said after she pulled into her driveway and got out of the car, she saw flames coming up by the trees. She wondered, “Is it the trees or is it the house? Because it was way, way up there. The flames were very high.”

Another nearby resident who called 911 said, “The bedroom windows were fully engaged in fire. The windows were actually exploding out into the driveway, so you heard large plates of glass breaking.”

Neighbors said the son was outside when first responders arrived.

Neighbor Mary Alfield, 72, who lives a few houses down, said she’s seen fires but never this big. “It was just a raging inferno,” she said. She saw fire coming out of the second floor on the left side, through a big picture window.

Her husband, Steve Alfield, said he saw one person being carried out on a stretcher, and firefighters smashing windows on the front and side of the house.

In addition to Mystic firefighters, Old Mystic, Noank Fire, Poquonnock Bridge, Ledyard and Submarine Base fire departments responded, along with Groton and Mystic River ambulances, L+M medics and Groton Town police. A Salvation Army canteen truck was on scene to provide refreshments to first responders. First responders were still on scene as of 8:40 p.m.

Eversource arrived to secure the power, and the state fire marshal was on scene.

Manfredi said there were no injuries to firefighters.

e.moser@theday.com