Providence and East Providence firefighters worked to extinguish a fire aboard a small powerboat in the waters off India Point Park Monday night. It is not clear at this point how the flames started, according to acting Providence Battalion Chief Stephen Capracotta. Two fire boats responded to the scene around 9 p.m. last night. No one was aboard the vessel when it caught fire. The powerboat reportedly sank below the surface so firefighters tied it to a tree in the park to secure it. Capracotta would not comment on the cause of the fire and says the U.S. Coast Guard and Environmental Police will handle the investigation. No injuries were reported.