An investigation is underway into how a python was able to escape from an exotic pet store, slither through the ventilation system into an apartment and strangle two young boys as they slept.

The two brothers, Noah Barthe, 4, and Connor Barthe, 6, were killed Monday while sleeping at a friend's apartment above a reptile store in the eastern Canadian town of Campbellton, according to the Royal Canadian Mounted Police.

The 100-pound, 15-foot African rock python, slipped out of its enclosure and slithered up through the ventilation system to the upstairs apartment, where it wrapped itself around killed the boys and killed them by constricting them, according to the preliminary investigation.

Autopsies are scheduled for the two victims today to determine the official cause of death.

The exotic snake has been put down by a veterinarian, police said in a statement, and a necropsy will be conducted to help determine what may have prompted the attack.

RCMP Sgt. Alain Tremblay told the Associated Press police were looking at whether the store followed the province's regulations on exotic animals.

"It's a criminal investigation," Tremblay said. "We're going to look at all avenues."

The owner of Reptile Ocean Inc., the exotic pet store where the incident took place, told the Global News television station that he has no idea how the snake escaped and is horrified.

"I thought [the snakes] were sleeping until I [saw] the hole in the ceiling. I turned the lights on and I [saw] this horrific scene," said Savoie, who caught the python in his living room, pinned it down and put it in a cage. "It's ridiculous. I can't believe this is real."

Authorities arrived at the apartment shortly after 6:30 a.m. Monday, where the two boys were found dead, Constable Julie Rogers-Marsh said in a statement.

While fatal snack attacks are rare, one expert says the incident was likely not a defensive attack, but the result of hunger.

"Snakes only constrict for food," Paul Goulet, owner of Little Ray's Reptile Zoo, told CTVNews. "And they're really hungry again before they eat."