Investigators said they were waiting for the results of an autopsy on Noah Barthe, 4 and his brother Connor Barthe, 6, as well as a necropsy on the snake before commenting further on the cause of death.
The snake apparently escaped from its enclosure, slithered through a ventilation system and fell through the ceiling into the room where the young boys were sleeping, authorities said Tuesday.
A snake expert said it was possible that the African rock python was spooked and simply clung to whatever it landed on. Police are treating the deaths in Campbellton, New Brunswick, as a criminal investigation.
The brothers had been visiting the apartment of a friend whose father owned an exotic pet store on the floor below, Royal Canadian Mounted Police Sgt. Alain Tremblay said. Tremblay said the 4.3-meter (14-foot) snake was being kept inside the apartment, not inside the pet store as authorities had previously stated.
Steve Benteau, a spokesman for the provincial Natural Resources Department, said no permit was issued for an African rock python, and provincial authorities weren't aware it was being kept at the apartment. The department said the snake is generally only permitted in accredited zoos, unless there is a special permit.
Tremblay said the snake was housed in a large glass enclosure that reached the ceiling of the apartment and escaped through a small hole in the ceiling connected to the ventilation system. He said the snake made its way through the ventilation system, the pipe collapsed and the snake fell.
The friend of the boys was sleeping in another room and was unharmed.
The pet store owner, Jean-Claude Savoie, told the Global News television station that he didn't hear a sound and discovered the "horrific scene" when he went into his living room on Monday morning.
Police said the snake was killed by a veterinarian. It was sent for a necropsy to confirm the type of snake and help understand what may have caused it to attack.
Reptile expert Bry Loyst, curator of the Indian River Reptile Zoo in Ontario, said police have been seeking his advice. He said police told him it wasn't the first time that the python had escaped its enclosure. Police were not available to confirm that late Tuesday.
Loyst said the boys had been playing with other animals hours earlier, and he believes their scent might have attracted the snake.
Paul Goulet, founder and co-owner of Little Ray's Reptile Zoo in Ottawa, said snakes don't recognize humans as a source of food, but if the children smelled like animals, it could explain an attack.
"If a snake sees an animal moving, giving off heat and smells like a goat, what is it? It's a goat," Goulet said.
Family spokesman Dave Rose, the boys' great-uncle, said the brothers had spent Monday at Savoie's family farm and played with llamas, goats, horses and dogs and cats before staying over at the apartment.
Snake expert John Kendrick, a manager at the Reptile Store in Hamilton, Ontario, said it sounds like the snake might have been spooked.
Pythons can sense heat, and if they are startled they can grab something, Kendrick said. He said their muscles run lengthwise through their body, so they are not very stable unless they are holding on to something.
It's possible that the python was just holding on to what it landed on, Kendrick said.
"Once they are in constricting mode, any part of their body that is touching something that moves, they'll wrap it," he said. "I've seen snakes with two different prey items at the same time, one with the back of the body and one with the front. It could have been an incident like that."