The two young boys killed by a python earlier this week were asphyxiated by the giant reptile, according to preliminary autopsy results released today.

Further tests are being done on the boys, but Royal Mounted Police Sgt. Alain Tremblay said, "We recognize that this has touched the hearts of people across the world and that people want to know how this could have happened."

"Our investigators are looking at all aspects of this tragic incident, and that will take some time," said Tremblay.

The autopsy results follow the disclosure by Canadian authorities that the python 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 Noah Barthe, 4, and Connor Barthe, 6, were visiting friends.

The 100-pound, 15-foot African rock python escaped from its enclosure in the apartment in the eastern Canadian town of Campbellton.

Reptile Ocean Inc. owner Jean-Claude Savoie had initially told the Global News television station that the snake had escaped from his ground floor pet store and slithered its way upstairs.

"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.

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. A necropsy, or an autopsy for animals, was performed on the snake, who was found to be in good health, said the police.

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."

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."

-ABC News' Alana Abramson contributed to this report.