Two males are dead and 10 others were treated for smoke inhalation after a fire consumed a rooming house in Toronto's Kensington Market early Thursday morning.

Twelve people were pulled from the building when emergency crews arrived at the scene on St. Andrew Street at around 2 a.m., Toronto police said. Two of the patients were children.

All 12 were transported from the scene to hospital, where two of the adult victims were pronounced dead, Toronto Fire Services told CP24.

The first crews arrived to the building, in the area of Spadina Avenue and Dundas Street West, to heavy smoke pouring from the second floor.

Seven occupants of the building were trapped and had to be rescued by ladder, Toronto Fire Capt. Mike Eckerman told media on scene: "It was pretty chaotic in the first few minutes."

The fire marshal is investigating the cause of the blaze, but it is believed that it began on the second floor and spread to the rest of the three-storey building while the occupants were asleep.

The building has restaurants on the ground floor and a cluster of small apartments on the second and third floors.

It is equipped with smoke detectors, but officials are unsure whether they were working at the time of the three-alarm blaze.