He said police are still investigating when the car went into the water and why, but said they did not suspect foul play.
The car had Rhode Island plates, and Gonsalves said he did not know whether it was a rental car or was owned by one of the women in the car.
The car was hauled out of the water by a crane around 8:30 a.m.
Newport police Capt. Russell Hayes told The Newport Daily News that one of the victims was from New York state and the two others live overseas. He said emergency personnel were notifying the victims' families and no other information was available.
The driver apparently missed a right-hand turn, Hayes told the newspaper.
"I'm not sure if they intended to take the turn here and missed it because it was dark and because of weather conditions," Hayes told the paper.
A dense fog advisory was in effect in Newport until 9 a.m.
The car went into the water near an area called the Travelift pit, the place in the marina where boats are lifted in and out of the water. Among the services the shipyard provides are dockage for luxury yachts and sailboats, as well as services for their owners, such as showers and workout facilities.
Coast Guard Petty Officer Ryan O'Hare earlier said that the car had been in the water for at least several hours. Newport Fire Department Deputy Chief Frank Young said firefighters wearing wetsuits and goggles discovered the women inside the car in the shallow water.
The shipyard is open 24 hours, and a security guard is posted at the entrance at all times.
A spokeswoman for the shipyard referred all questions to police.