More than 30 elderly people are feared to have died after a fire swept through a retirement home in Quebec, Canada. 

Quebec police confirmed five fatalities from the blaze, while three dozen more remained unaccounted for as rescuers searched for more victims.

The search and an investigation into the cause of the fire were hampered by up to 30cm of ice covering the wreckage after water used to douse the fire froze.

"We could hear screaming from inside. The fire was intense, it was like a haystack on fire," witness Pascal Fillion told Radio-Canada.

The 52-unit home is in L'Isle-Verte, a small town 450km northeast of Montreal with a population of around 1,400 people.

It housed around 50 to 60 elderly people, half of them more 85 years old.

The town's acting mayor, Ginette Caron, told a news conference that most residents of the home are reliant on caregivers.

She said these include elderly people needing "100% care, almost all in wheelchairs, using walkers, or who aren't mobile at all, people suffering from the late stages of Alzheimer's.

"The types of services offered here are not found just anywhere. That's what we've also lost," she said.

Authorities said 23 people were evacuated from one third of the building. They said 13 of them were injured, one seriously, and were treated at nearby hospitals.

Two firefighters were also hurt.

Fire chief Yvon Charron said his crew hopes to breach the remaining areas worst hit by the flames in the coming hours "to search for any bodies."

The Red Cross set up a makeshift shelter at a local school where several people rescued from the inferno spent the night, according to a representative, Myriam Marotte.

Some residents might have been away visiting family, or may have taken refuge elsewhere during the blaze and missed being counted, she told local television.

"It's a tragedy for the community and we can only fear that the death toll will rise," provincial Minister Gaetan Lelievre told Radio-Canada.

Flames engulfed the wood-frame building, leaving only the fireproof elevator shaft standing by morning, with a mound of rubble all around.

An adjacent pharmacy and a community centre were also destroyed.

Initial indications suggest that the oldest part of the building was not equipped with an automatic fire sprinkler system.

A full investigation is under way to determine the causes and circumstances of the tragedy.

A witness said his grandmother "had called her son to come rescue her, but he didn't succeed. He tried to use a ladder to reach her, but she died right there on the balcony".

Quebec Premier Pauline Marois sent a message from Davos, Switzerland to say she was "profoundly saddened by this tragedy" and vowed government help for the victims and their community.

One of two brothers waiting outside a police cordon to learn their elderly mother's fate said it was an "awful way to die, in the dark and the cold, and afraid".