BOOTHBAY, Maine (NEWS CENTER) — Investigators continued their search Monday for the cause of a deadly fire in Boothbay over the weekend that left two people dead.

Six people were inside the home on Pleasant Cove Road when the fire broke out Sunday morning. Four of them managed to escape the burning building, including 48-year old Julie Gilbert. She jumped out a second-story window. Gilbert lost her son, Lucas Farias, and her boyfriend, Bart Zamora. They were trapped inside.

“Firefighters attempted to extinguish the fire and rescue individuals but the fire was too intense for them to get inside," said Sgt Joel Davis of the state fire marshal's office. "Two people have died as a result of the fire."

An investigator was back at the scene Monday, posting the home in hopes of keeping people out while the investigation continues. It appears the fire started in the first-floor living room. The cause is still unknown.

Julie Gilbert is formerly from Damariscotta; she’s now from Chicago, as were the two victims. They were renting the home and had been celebrating her boyfriend Bart Zamora’s 50th birthday.

We spoke by phone with Bart Zamora’s brother, Wayne, in Chicago. He said investigators told his family Zamora managed to get the upstairs window open to allow his girlfriend to jump to safety. In doing so, he put his own life in jeopardy because the oxygen that came in helped fuel the flames.

Neighbor Carl Schmidt said his wife spoke with Gilbert moments after she jumped to safety.

“When my wife got here, the woman was still smoldering because she caught fire," he said. "When they broke the window, the back draft, the whole room exploded with flames. She got out and got put out, fortunately. I don’t know how bad her injuries were."

Gilbert was transferred to Maine Medical Center for treatment. The other three people were treated and released. Investigators were planning to spend the day interviewing them, in hopes of learning more about what was happening in the house Sunday morning.