(CNN) -- Sunday had been a ball for Noah and Connor Barthe.
Noah, 4, and Connor, whose 7th birthday was coming up, spent Sunday afternoon playing in a pool, shopping for treats and playing with animals at the farm of a family friend. They even got to steer a tractor, said their great-uncle, Dave Rose.
"That's the type of life they had, and that's what we're going to try to remember," Rose told reporters Tuesday in Campbellton, New Brunswick.
Then sometime before dawn Monday, a 100-pound snake came crashing through the ceiling of the apartment where they were spending the night. They were found dead there Monday morning, apparently victims of an African rock python more than 10 feet (3 meters) long, the Royal Canadian Mounted Police said.
Autopsies were being performed on the boys Tuesday afternoon, RCMP Sgt. Alain Tremblay said. A reptile expert is assisting the Mounties in their investigation, and the snake has been euthanized, he said.
The apartment was the home of Jean-Claude Savoie, a family friend whose Campbellton pet store was downstairs. But Tremblay said the python was kept upstairs in a custom-built glass enclosure similar to an aquarium.
The cage reached the ceiling, and the snake was somehow able to crawl through a vent into the building's ductwork. It was above the living room, where the boys were sleeping, when the ceiling fell in.
No 'regular case' for the Mounties
The snake was found in the same room as the boys, Tremblay said, but he would provide no further details. He said the RCMP is conducting a criminal investigation but wouldn't discuss possible charges.
"Obviously, it's not a standard or regular case," he said. "It's very traumatic for the family that this happened. But for the police, this is an investigation where there's a loss of life, and our approach to analyze a scene is almost identical, although here we're dealing with a reptile."
Rose said pet store owner Savoie and his family are longtime friends of the boy's family. It was his family farm they went to Sunday afternoon, and both families were together until midnight, Rose said.
"They were two typical children who enjoyed life to the maximum," he said.
Savoie told the Canadian website Global News that he came upon the awful sight Monday when he entered the living room.
"I thought they were sleeping until I seen the hole in the ceiling. Everything had fallen. And I turned the lights on and I seen this horrific scene," said in a phone interview with the Canadian website Global News.
Savoie said he located the reptile in a hole.
"I pinned him down and put him in a cage," he said.
Savoie has spoken briefly with investigators and is expected to meet with them again, Tremblay said.
Neighbor expresses shock
Canadian broadcaster CBC reported that the python is between 11 and nearly 15 feet long and weighs more than 99 pounds.
A neighbor, Diane Fournier, has lived on the same street as the pet store for 12 years. She described the deaths as "shocking."
"I knew the kids. They were brothers," she said. "They played in my yard with my dogs all of the time."
Fournier sent CNN a photograph her husband took of the pet store. It showed police cars, cones and yellow tape blocking off the area.
The store, Reptile Ocean Inc., offered condolences on its Facebook page Monday before the page was shut down.
A 1996 report by the animal protection charity Zoocheck and the World Society for the Protection of Animals listed Savoie as the owner of Reptile Ocean.
It described him then as "a young enthusiastic amateur collector who has only recently embarked on this commercial venture."
'I can't believe this is real'
According to Global News, Savoie said that the two boys were the children of his best friend and that they often slept over at his apartment.
"I have so many mixed emotions right now, it's ridiculous," he said. "I can't believe this is real."
Deaths caused by large constrictor snakes like pythons are fairly rare.
The Humane Society documents 17 people who have died in incidents in the United States related to the snakes since 1978, 12 of them since 1990.
But scores of adults and children have been hurt in attacks by the reptiles, the society said in a report this year.
"Children, parents, and authorities are finding released or escaped pet pythons, boa constrictors, and anacondas all over the country, where they endanger communities, threaten ecosystems, and in many cases suffer tragic deaths," the report says.
In Canada, a man in Ontario was killed in 1992 by his pet python, the Globe and Mail reported, citing Melissa Matlow, a spokeswoman for the World Society for the Protection of Animals in Canada.
CNN's Kevin Conlon contributed to this report.