The python that strangled two young boys this week did not escape from the pet store below the apartment where the boys slept, as previously believed, but was a house pet kept inside the apartment where they were visiting friends, authorities in Canada said.

The 100-pound, 15-foot African rock python escaped from its enclosure in the apartment in the eastern Canadian town of Campbellton, where Noah Barthe, 4, and Connor Barthe, 6, were sound asleep Monday, Royal Mounted Police Sgt. Alain Tremblay said Tuesday.

"It was upstairs," Tremblay said at a news conference Tuesday evening. "[It] never got out of the store."

Escaped Python Kills 2 Boys in Canada

Reptile Ocean Inc. owner Jean-Claude Savoie had initially told the Global News television station that he had no idea how the snake escaped from the pet store.

"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."

The python wrapped itself around the boys and constricted them, according to the preliminary investigation. Autopsies were scheduled for the two victims today to determine the official cause of death.

The exotic snake was captured in the same room where the boys were found. It has been killed by a veterinarian, police said in a statement, and a necropsy will be conducted to help determine what might have prompted the attack.

Tremblay told The Associated Press that police were looking at whether the store's owner, who lives in the apartment above and was the boys' father's best friend, followed the province's regulations on exotic animals.

Store owner Savoie said he didn't hear a thing, and came in to find the scene. He had owned the python for 10 years.

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

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 snake 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 in Ottawa, told CTVNews. "And they're really hungry again before they eat."

Dave Rose, the uncle of the two brothers, said the family will try to remember them for the fun lives they had. He said before the sleepover, the boys spent the day swimming, shopping and visiting a family farm.

"They played with llamas and goats and horses," he said. "They played with dogs and cats in the hay loft. They went for a ride in the farm tractor, which I'm told they even let them steer the tractor, so they had a super day."