Newport Fire Capt. Brad Cronin said there were two people on the vessel at the time of the fire and were transported to Newport Hospital.
The 40- to 50-foot vessel was on a mooring in the harbor, Cronin said. The emergency call came in around 12:56 a.m. The fire department dispatched an incident command car, a rescue wagon and the Marine 6 vessel.
The U.S. Coast Guard and Narragansett Bay Marine Task Force also responded. The fire was under control by 1:26 a.m. The vessel sank during firefighting efforts.
Cronin said the cause of the fire is under investigation. The state Department of Environmental Management will assess the environmental impact, he added.