Police have released the names of three teenage sisters and their aunt found dead in a submerged vehicle Tuesday in a part of the Rideau Canal northeast of Kingston, Ont.

Kingston police have identified the victims as Zainab Shafia, 19, Sahar Shafia, 17, Geeti Shafia, 13, and Rona Amir Mohammed, 50. All were from the Saint-Leonard borough in Montreal.

The Nissan Sentra was pulled out of the Kingston Mills Locks after it was discovered submerged early Tuesday. (CBC)

Investigators were still unable to say what happened to the four victims, whose bodies were found Tuesday morning inside a four-door Nissan Sentra that was underwater at the northernmost lock of Kingston Mills Locks.

Kingston police Const. Mike Menor said investigators are conducting tests on the car but told reporters it could be weeks before the results of autopsies being performed Thursday are released.

Mechanics also inspected the car to see whether it malfunctioned in any way.

“We’re still trying to ascertain the why, the why, the why,” Menor said. "We're waiting with bated breath here."

"This is a very emotional incident," Menor said, his voice breaking. "You know what bothers me is the fact that there's three sisters, and it bothers us."

John Bruce, a Parks Canada employee at the Kingston Mills Locks, found the car submerged in about three metres of water after noticing an oil plume.

"I saw some oil rising out of the water. And when I looked to see why the oil was coming up, I saw the outline of a car," he said.

Bruce assumed the car had been stolen and then ditched.

Travelled through poles

Staff Sgt. Chris Scott of the Kingston police speaks during a press conference Tuesday. (CBC)The lockmaster from the Rideau Canal told investigators the locks were closed for the night and secured, said Staff Sgt. Chris Scott of the Kingston police.

The case has left police puzzled as to how the car left the road, travelled down a patch of grass — either over a concrete barrier or through a gate — and through two of the poles on the dock.

Scott added the women had earlier stopped in Kingston for the night.

"We pieced together that they did have a bit of a family vacation west of us on the other side of Toronto and were returning to Quebec," he said.

Meanwhile Thursday, Montreal police said they received a request from investigators in Kingston to locate a second vehicle in the city's north-end St-Leonard borough.

Montreal police spokesman Daniel Lacoursière would not say whether officers had found the vehicle. He also wouldn't confirm reports that the second vehicle might have been seen in Kingston with one of the victims.

The incident has left people in the Kingston area in shock. People have left flowers near the lock where the car was found.

With files from The Canadian Press