According to public safety spokesman Steve McCausland, the bodies of Autumn Bryant, 44, and her husband, 48-year-old Kenneth Bryant were discovered at a home on Fairview Street late Tuesday morning.
Investigators said Kenneth Bryant shot his wife then turned the gun on himself.
McCausland said in a release that Autumn Bryant died after being rushed to Maine General in Augusta, and Kenneth's body was found outside the home in a truck.
In a statement, McCausland said the two were an estranged couple in their 40s who lived in Livermore Falls.
The two became separated in November and, according to McCausland, Autumn Bryant had been living at her brother's home in Gardiner, which is where the shooting took place.
Autopsies on the bodies were expected to be completed Wednesday.
McCausland also said the shooting was connected to a house fire in Sidney Tuesday morning.
Authorities said Autumn's Bryant's mother, Terry Gilman, and her husband Lawrence own the home on Messalonskee Lake, which was destroyed by flames.
McCausland said the house was unoccupied at the time.
The cause of the fire remains under investigation.