It’s almost unthinkable—a 12-foot-long, 100-pound African rock python falls from a ceiling in the middle of the night, lands on two young boys, and kills them.

Yet that’s the story that police in the tiny Canadian town of Campbellton, New Brunswick, are trying to piece together after the bodies of Connor Barth, 4, and his brother Noah, 7, were discovered Monday morning in an apartment above an exotic pet store. Meanwhile, as the community grieves, animal-rights groups are calling for a ban on keeping the snakes as pets—and reptile experts are debating whether the creatures are truly capable of such a horrific act.

“Originally we thought it strangled the boys,” said Jullie Rogers-Marsh, a constable with the Royal Canadian Mounted Police, “but now we aren’t confirming exactly what happened until we get autopsy and necropsy results.” She did confirm that the snake did “attack” the Barths in some way. “We feel for the family involved, and we are working hard to determine the cause of death,” she added.

Rogers-Marsh said the autopsies were performed on the children on Tuesday. A necropsy was also performed on the python to figure out “if there was something wrong with the snake, and what caused it to attack,” she said.

The snake, which can grow as long as 20 feet, was kept in a glass enclosure on the second floor of the building, where the pet store owner, Jean-Claude Savoie, lived with his son. It is believed the snake escaped through the top of its cage into the ventilation system in the ceiling and slithered its way into the living room, where the young boys were sleeping.

According to Rogers-Marsh, the boys were good friends with Savoie’s son and were spending the night at the second-floor apartment when the tragedy occurred.

The boys were discovered the following morning by Savoie, who called the police shortly after 6:30 a.m. Savoie told the Canadian television network Global News he found the children in the living room with a hole in the ceiling above them. “I thought they were sleeping until I [saw] the hole in the ceiling,” he said. “I turned the lights on and I [saw] this horrific scene.”

He said he was able to capture the snake and put it back in its cage before police arrived, at which point they took it away and euthanized it.

Ian Comeau, deputy mayor of Campbellton, says he believes the ceiling may have collapsed because of the weight of the snake, and the snake “would have fell on the bed where the two kids were.”

For some, the event isn’t as shocking as it seems. Rob Laidlaw, executive director of Zoocheck, a Canadian animal protection charity, says such attacks are rare but not unheard of. “It doesn’t happen every day, but it’s not uncommon either,” he said. “The deaths are the most sensational part of it, but there are a large number of people suffering some sort of injury such as a python biting an owner. Human injury is probably larger than most of us believe.”

The last reported attack on a human by an African rock python occurred in 2002, when a snake swallowed a 10-year-old boy in Durban, South Africa. Three years earlier, in 1999, another rock python killed a 3-year-old boy when it escaped its cage in Centralia, Illinois.

Laidlaw says it is difficult to say at this point what may have caused the big snake, which usually feasts on rodents and birds in captivity, to attack the young boys, but it could have been fear. “The fact it didn’t try to consume the kids might indicate it was scared,” he said. “It’s conceivable it could have been fearful of a situation it hadn’t been exposed to before.”

Python attacks are particularly horrendous, says Laidlaw. “There is a lot of strength in those snakes,” he said. “They are very large and robust. That size of snake is not a snake an adult could handle.

Jay Brewer, who founded the Reptile Zoo in California and has worked with rock pythons, acknowledges that the rock python has an ornery disposition—”typically they lunge at you,” he says—but says he doesn’t believe the snake killed the Barth boys, an opinion echoed by several other snake experts.

“It doesn’t sound logical,” Brewer says. “It’s paranoid, so it will immediately go on the defensive, but it won’t wrap you up and kill you. They generally don’t want to constrict you. I would like to see absolute proof it was guilty. It just doesn’t jive. I don’t know how [the boys] wouldn’t have got up and run away. The dots don’t quite connect.”

“I’m totally skeptical,” Johan Marais, who runs the African Snakebite Institute in South Africa, told the National Post. “It just sounds very, very strange.” The snakes only eat a few times a year when in captivity, he added. “Snakes don’t kill for fun. It takes far too much energy.”

“Snakes get a bad rap,” Brewer noted. “They get blamed for everything. The truth of the matter is a German shepherd is 100 times more likely to kill you.”

Even still, African rock pythons are extremely easy to purchase in North America, especially in the U.S. “The whole reptile business is a thriving trade,” according to Laidlaw. “The U.S. is the No. 1 destination for wild-caught and ranch-bred reptiles. There are a lot of private breeders and importers involved. You’re talking about several million reptiles in legal trade a year.”

That’s not the case in Campbellton, a tiny town of 7,500 people in the province of New Brunswick, some 100 miles from the Maine border. There, a special permit is required to keep that species of snake; Savoie did not have one.

"It is illegal for anyone to keep any exotic species that is not listed in the regulation unless they have a permit from the Department of Natural Resources," a spokesman for the New Brunswick Department of Natural Resources confirmed in a statement this week. "If such an animal is found, it will be confiscated and the person who possesses the animal can be charged under the Fish and Wildlife Act."

So far, no charges have been filed against Savoie. But city and provincial officials are now taking a closer look at the almost 20-year-old Reptile Ocean, his pet store, which was once a popular educational and vocational center; in the fall, students would go with their teachers to see the animals.

“We are not labeling it as a criminal investigation at this point,” said Rogers-Marsh. “It could change but right now we are focusing on investigating the deaths of the two children.”

Comeau, the deputy mayor, says that the community wants answers. Meanwhile, a small shrine with teddy bears and candles has sprouted up outside the pet store that still remains cordoned off with yellow police tape. “It is horrific and tragic for those two young kids,” said Comeau. “A lot of people are upset. It is a close-knit community.”

“It is so horrible I can’t imagine how the mom is dealing with this,” said Melissa Matlow, spokeswoman for the World Society for the Protection of Animals in Canada. “It is beyond belief. We call for an outright ban of keeping them as pets. I don’t think we need more evidence. The tragedy speaks for itself. There is simply no need for it. Any benefit doesn’t outweigh the significant public safety risk. These snakes don’t like to be kept in tiny places.”