Forest rangers and local fire departments are responding to a large forest fire on Sheep Island in Casco Bay. Plumes of white smoke rose from the fire Friday afternoon, and a ranger helicopter was en route to the island, according to a Tweet from the Maine Forest Service. Photos and statements posted on Twitter from the forest rangers indicate that multiple homes are in danger, and the chopper will begin dropping buckets of water onto the flames. Sheep Island is located off Harpswell. This story will be updated.