One man was left dead and three people were sent to hospital early Sunday in Montreal after stabbings by a 26-year-old who suffered a breakdown, Canadian police said.

Police in Canada's second-largest city said they responded to an emergency call at 6.50am (1050 GMT) "concerning a man in crisis" in an apartment in downtown Montreal.

The suspect "stabbed with a sharp object" his mother and stepfather, then stabbed another person in a neighbouring apartment as well as a doorman who tried to intervene, police said in a statement.

The stepfather, aged 72, died at the scene while the three other victims were taken to hospital, where one remains in critical condition.

The suspect was arrested at the scene, said police.

Usually staid Canada has seen a recent jump in violent attacks and mass killings that have left 43 dead and 38 wounded since 2017.

These included a truck attack on a Muslim family in London, Ontario, a shooting rampage by a man posing as a Mountie in Nova Scotia, a van attack on pedestrians in Toronto and the killings of worshippers at a Quebec City mosque.