Ottawa police used explosives to blow a hole in the ice at Fitzroy Harbour Monday night in the hopes of extracting a vehicle submerged in the Ottawa River, believed to belong to Donna Graves. The 61-year-old remains missing along with her 29-year-old son Daron, who were last seen Thursday evening.

Recovery efforts have been ongoing after police divers found one body inside the submerged car, upside down in more than two metres of water at the end of Ferry Road in Fitzroy, a suburb in Ottawa's far west end.

Police planned to extract the car with a crane Monday afternoon, but cold weather and other logistical complications, including overhanging power lines, delayed the recovery efforts. But CBC reporter Judy Trinh reports that if conditions are safe, police will attempt to bring the vehicle to the surface Monday night.

West division Staff Sgt. Patrick McCaffery said the vehicle matches the description of the Black 2013 Dodge Dart belonging to the Graves family.

While police have said one body was located in the car, they have not been able to positively identify the victim.

The mother and son were last heard from as they left The Prior Sports Bar and Restaurant in Arnprior, Ont., at 11 p.m. ET Thursday.

Donna and Daron Graves have been missing since Thursday night. (Supplied photos)

David Graves, Donna's husband and Daron's father, said his wife had called him Thursday night and said they were on their way home, but they failed to show up.

Graves said he doesn't believe they drank too much and said it was understood that if someone needed a ride home, he would come and pick them up.

Over the weekend, grief counsellors were also at the Graves's home on Ferry Road, within sight of the recovery operation.

Dropping temperatures obstacle for dive teams

The police marine diving unit said a crane was expected to arrive in the afternoon to help remove the vehicle from the river, but the extreme cold prolonged recover efforts.

Police were waiting on the Ottawa River in the city's far west end for a crane to help recover a vehicle and body submerged in about nine metres of water. (Stu Mills/CBC)

The windchill Monday made the temperature feel like –30 C in the Ottawa area, leading to a frostbite advisory. The cold can also cause fatigue among members of the diving unit, police said, adding to the challenge of extracting the car.

"It's not so much whether there is daylight remaining, but whether after the cutting and setup the divers are too fatigued to begin," said Staff Sgt. Marc André Sheehy.

Car located in river Saturday night

Police began investigating the river Saturday close to the home when they saw skid marks on the road and debris left behind, suggesting a vehicle struck the wharf and was in the river.

Dive teams located a car in the river Saturday night. Police at the scene said they were treating the incident as a car accident and said speed may have been a factor in the crash.

The vehicle had rolled over and was upside down more than eight metres underwater and about 40 metres from the jetty.

Originally, police considered cutting channels into the ice to drop cables to attach to the car, and then further cuts to allow a crane to lift the vehicle out of the water, said McCaffery. However, police have opted to use explosives and said there would be no impact to the vehicle as the depth of the water would cushion the blast.

The coroner will not be at the scene until the car and body are removed, police said.