Canadian Prime Minister Justin Trudeau has called the incident a "tremendous loss".
Seven children from a family said to be Syrian refugees lost their lives early Tuesday in a fire that swept through their house in the Canadian city of Halifax, police said.
"There are seven fatalities resulting from the incident," police in the Atlantic seaboard city said.
"All deceased are believed to be young children from the same family. A woman and a man remain in hospital."
At a press conference, police said the man had "life-threatening" injuries.
Public broadcaster CBC said the victims were Syrian refugees.
The cause of the fire was not immediately known.
A neighbour, Danielle Burt, told CBC that she heard an explosion in the middle of the night before seeing the flames ravaging the home.
"I heard a huge bang, and I was laying in bed with my daughter, followed by a woman screaming, so I jumped up out of bed and looked out the back window and all I could see was flames shooting out from the back door going out onto their deck," she said.
Firefighters responded at 12:40 am.
In a Twitter message, Prime Minister Justin Trudeau said his "heart goes out to the survivors of this horrible fire ... and loved ones who are mourning this tremendous loss.
"Words fail when children are taken from us too soon, especially in circumstances like this."