Friends, neighbours and co-workers are reeling after learning a Toronto couple and their two children died in a Christmas Eve fire at their cottage near Peterborough, Ont..

Residents in Toronto's Riverdale neighbourhood confirmed that the victims are Geoff Taber and Jacqueline (Jacquie) Gardner, and their sons Scott, 15, and Andrew, 13.

Ontario Provincial Police have called the incident a "Christmas tragedy."

Autopsies will be performed on the bodies to determine the cause of death, the OPP said in a news release. Three bodies have already been sent to the officer of the chief coroner in Toronto. The fourth has not yet been transported. All four bodies have been removed from the structure.

Police said the investigation is continuing.

'A glow in the sky'

"It's been extremely difficult for us to get heavy equipment into the scene to assist us," Wayne Romaine, an supervisor with the Ontario Fire Marshall, told CBC News..

Romaine said the cottage's remote location played a part in how much the blaze developed before it was detected.

"The first person that actually report[ed] seeing this fire was seeing a glow in the sky and the entire main floor was engulfed in flames," Romaine said.

The OPP have not yet released the names of the victims.

Geoff Taber and Jacquie Gardner, along with their two sons, are believed to have died in their family cottage near Peterborough, Ont., after a fire broke out Christmas Eve. (Facebook)

Friends described the family as vibrant.

"They were lovely, open, giving and social. Their kids were beautiful ... just remarkable people," said Anne Donald, who calls herself a close friend of the family, and who recalled walking her dogs with Taber and Gardner.

Donald also said the cottage was a gathering spot for the family and that they frequently hosted guests.

"[The family] was really excited about going up to the cottage and celebrating Christmas up there."

Taber was 'a legal visionary'

Taber and Gardner were registered lawyers. Taber was a partner at Osler, Hoskin & Harcourt LLP. Gardner was with Altamira Investment Services Inc.

Dale Ponder, chief executive at Osler law firm, said in a statement that Taber "was a generous, vibrant and wonderful person, a legal visionary and beloved partner at Osler. There are no words adequate enough to express the depth of sorrow we feel."

"Jacquie was an exceptional corporate lawyer initially at Osler, then as general counsel and secretary at Altamira Investment Services."

Their sons are remembered as lovers of sports and avid hockey players.

Gardner was a registered lawyer and remembered as a volunteer in her community. (Facebook)

First responders were called to the cottage on Hamilton Drive North after 4 a.m. ET on Saturday. No survivors were found.

Mary Sharp, who lives across the street from the Taber home in Toronto, said the family had lived on Bowden Street for "13, 14 years".

Sharp said Gardner had stopped practising law for a few years to take care of her children. She described Gardner as being generous with her time.

"She volunteered at [the children's] school and at East General Hospital. Just very, very good people."

Sharp added: "It's terrible, many people don't know yet."

Gordon Cheong, another friend and neighbour on Bowden Street, went road cycling regularly with Taber, and last saw him before Christmas Eve. Cheong said the couple planned to retire at the cottage near Stoney Lake.

On Sunday, after hearing the news of his death, his cycling group the Riverdale riders awoke early to ride in his honour.

Search through rubble continues

Police are continuing the search through the rubble of the cottage, but said "there is nothing left."

Ontario Provincial Police are still investigating the fire. (Postmedia Network)

OPP Const. Jason Folz said the task of finding a family dead on Christmas Day was "devastating" for police and the fire department.

The cause of the fire is not yet known. Romaine says investigators are looking into the role that a baseboard heating system and a propane tank may have played, as well as whether candles may have been in use. Officers are also trying to determine whether any working smoke alarms were in the cottage.

Police say they will not formally identify the victims until postmortem examinations have been completed. Next of kin have been notified.