State fire officials are investigating the cause of two separate fatal fires, both reported on Sunday morning.

The first fire was reported at a home on Sea Mist Lane in Harpswell. Investigators from the fire marshal’s office arrived after the fire was put out by the Harpswell Fire Department, and were told the building was believed to be an unoccupied seasonal home, said Shannon Moss, spokesperson for the Maine Department of Public Safety.

As investigators tried to determine the fire’s origin and cause, they discovered a man dead inside the house. His identity will be determined by the medical examiner’s office in Augusta.

Because of the extent of the damage, the fire was classified as undetermined, but remains under investigation.

The second fire was reported just after 9 a.m. at 9 Usen Lane in Old Orchard Beach.

The Old Orchard Beach police and fire departments were called to the home for a reported cardiac event, but found a man dead in the living room, and a fire had occurred in the house.

The man was identified as 70-year-old John Chadbourne.

The cause and circumstances of that fire are being investigated.