PORTLAND — Investigators are still trying to determine what caused a fire that destroyed a seasonal home on Peaks Island and damaged a nearby home.

Witnesses alerted the firefighter assigned to the island that smoke was coming from a house at 160 Upper A. St. at 11:45 p.m. Sunday.

The island’s volunteer fire crew responded and Portland’s fire boat transported 17 firefighters to the island.

The fire destroyed that house and spread to the adjacent one before firefighters brought it under control at 4:30 a.m. Monday.

Neither building was occupied and nobody was injured.

Authorities say there is no indication at this point that the fire is connected to today’s burglary arrest.