Tooba Mohammed Yehya, mother of the three girls found dead in a car in a Rideau Canal lock in Kingston, Ont., was grief-stricken on Friday, saying she still wasn't clear on what caused the accident. (CBC)

A Montreal family was struggling to deal with its grief on Friday after four family members were found dead in a car in a Rideau Canal lock in Kingston, Ont.

“I cannot talk, I'm so sorry, I cannot talk,” cried Tooba Mohammad Yehya, mother of the three teenage sisters who were found dead in the canal.

Mohammad Yehya confirmed the girls were three of seven siblings in the family. The girls are survived by two sisters and two brothers.

Mohammad Yehya explained that the family stopped in Kingston on the way back from a trip to Niagara Falls in two separate cars.

She said her 19-year-old daughter, Zainab Shafia, got the keys to one of the cars, saying she wanted to get some clothes from the vehicle. Mohammed Yehya admitted her daughter was not an experienced driver, having driven only on a few occasions.

After Shafia took the keys, Mohammed Yehya said she doesn't know what happened. Sometime during their overnight stay, she said one of the family's two cars disappeared.

The girls’ father, Mohammad Shafi, confirmed on Friday the four women who died were all staying in the same hotel room in Kingston. Five other family members, including Shafi and his wife were staying in a separate room.

Shafi said it was police who broke the news to him Tuesday morning that his daughters and 50-year-old cousin had been found in a sunken car in the Rideau Canal. Shafi said he went down to see the area with his own eyes but could not piece together how it happened, although he did say the girls had “no idea how to drive.”

“One family, four people died.... no good,” Shafi said in broken English from his home in Saint-Léonard. He said he spoke to Kingston police on Friday but still had no idea when the women’s bodies would be returned to the family.

Saif Fazel, a cousin of the three teenaged girls, said the entire family is in shock. He said he has hardly slept since hearing about the incident from the girls' mother.

Fazel said the family has dozens of relatives in Quebec, all of them immigrants from Afghanistan. He said the irony of the girls' deaths is hard to deal with.

"What we did, what we went through …to save our lives, you know? From the Russians, from all those events in Afghanistan, and all of a sudden you know, we're in Canada … we said okay, we are safe finally. And there you go … we lost three members of our family in an accident," said Fazel.

Fazel said his young cousins were very caring toward their parents and at least one girl planned to become a doctor. Now Fazel said the big question for the family is how the car ended up in the water.

Kingston Police Const. Michael Menor said investigators are treating the case as suspicious, until they know more. He said they are trying to figure out who was driving.

“That's all part of the investigation and I know the detectives are keeping a lot of that information close to their chests,” said Menor.

Autopsies are being performed on sisters Zainab, Geeti, 13, and Sahar Shafia, 17, and relative Rona Amir Mohammed, 50, who also died in the accident. The woman was a cousin of the girls' father.

All were from the Montreal neighbourhood of Saint-Léonard. Investigators are baffled by how their car left the roadway and ended up underwater.

Police check surveillance videos for clues

Kingston Police were checking surveillance video on Friday from two nearby gas stations to see if it can provide any clues as to how the car made it past several barriers and ended up submerged in the lock.

Cynthia Waran, who owns Code's Corners convenience store near the Kingston Mills lock where the car was found Tuesday, said police came on Friday to look at footage from the past week. She said the officers left without saying anything. Waran said she didn't see anyone matching the description of the car's passengers earlier this week.

Sumit Kumar, who runs the Stop and Save across the road, said police were at his store on Tuesday and again on Friday to go through his digital surveillance.

With files from The Canadian Press