Connor and Noah Barth, aged seven and five, were killed side by side when the animal landed on them from above and attacked them while they slept.
Their bodies were discovered by Jean-Claude Savoie, the owner of the flat and the pet shop, who said it was a “horrific scene”.
He fears the creature wrapped itself around them both as they lay together on the floor during a sleepover.
Police in Canada have begun a criminal investigation, but so far no arrests have been made.
Fighting back the tears, Mr Savoie, whose Reptile Ocean shop is in Campbellton, New Brunswick, said the boys were his “best friend’s kids” and that they were like an extended family to him.
Recounting the moment he found them – at 6am on Monday – he said: “They didn’t even open their eyes or nothing. I thought they were sleeping until I saw the hole in the ceiling.
“I turned the lights on and I saw this horrific scene. My body is in shock. I don’t know what to think. I feel like they’re my kids.”
Python attacks are rare even in the wild and Canada has been left in shock that this could happen, especially those living in
remote Campbellton, which has a population of 7,400.
The snake was an African rock python, which is normally found in the south and west of the continent and, while not venomous, can devour antelopes or crocodiles in one go.
They kill their prey by wrapping their bodies around them and constricting them until they can no longer breathe.
The last such attack was in 2002 in Durban, South Africa, when one ate a ten-year-old boy whole, the first recorded “man-eating” incident for the species.
On Sunday night, the boys had been playing in the lounge as they always did when they stayed over at Mr Savoie’s. It is not clear how the snake got free as its cage had two locks on it.
At some point overnight, after wriggling out, it went up a ventilator shaft into the flat above and dropped down on the boys.
Mr Savoie, who called the deaths a “terrible accident”’, found it curled up after the attack and put it back in a cage. His son, who was sleeping in another room, was unharmed.
The dead boys’ mother, Mandy Trecartin, lives close to the Reptile Ocean store. Their father has been named as
Andrew Barthe from the nearby town of Dalhousie.
Melissa Ellis, a family friend, said: “There are no words to say that could sum up the joy and love they brought us all.
“They were loved by every hand that touched them, and the heavens said it all today as even the angels were crying.”
According to snake experts, the African rock python is not known for being aggressive,
although it could have been hungry and smelled food.
Alexandre Tremblay, who sells exotic snakes in Montreal, said: “For a snake of that size to be able to get out, it just has to be really hungry and not in good conditions. Because usually snakes are very easy-going … it’s rare that snakes get out.”
Post-mortem examinations were last night due to be carried out on both boys to find out
exactly how they died.
According to reports, Mr Savoie had all the necessary
licences for the snake, which is currently in the custody of the Royal Canadian Mounted Police (RCMP) and is expected to be
The RCMP said in a statement: “The preliminary investigation has led police to believe that a large exotic snake had escaped its enclosure at the store.
“It got into the ventilation system, then into the upstairs apartment. It’s believed the two boys were strangled by the snake.”