A 22-year-old man and an 18-year-old woman are dead following an overnight fire in the St. Raymond's Parish of NDG.

The fire began around 4 a.m. at 5563 St. Jacques St. W, where emergency crews found two people on the second floor whose hearts had stopped.

"They were very quickly taken outside in cardiac arrest, the CPR was started on these two victims," said fire chief Ian Ritchie.

The 22-year-old man was declared dead soon after the discovery but it was hoped that the 18-year-old woman would survive, as she was listed in critical condition for most of the day.

However her condition did not improve and she was pronounced dead around 7 p.m. Friday evening.

The young man was described as a visitor to Montreal - reportedly from Victoria B.C. - but no details were provided concerning the identity of either victim.

Two other people were hurt badly enough to require medical treatment in hospital but their lives are not in danger.

Firefighters evacuated about 50 people from the three-storey building soon after the fire began.

Jazz musician Eric Dew said that the blaze claimed most of his belongings, all of which were uninsured.

"Everything I own, musical instruments. I’m a musician and now I don't know," said Dew, whose smoke detector was not functioning at the time of the fire.

Firefighters got the fire under control after about two and a half hours but cautioned that it would take more time to extinguish the flames and all hotspots.

Montreal's arson squad is investigating the blaze, as they do with all fires that claim human lives.

Police found a basement marijuana grow-op in an adjacent building but said that it was not related to the fire.