A snake expert in Halifax says she was shocked and saddened to hear that a large snake killed two little boys in Campbellton, N.B.

RCMP said the python got out of its cage from Reptile Ocean, and got up to an apartment on the second floor through an air vent.

The two boys, Noah Barthe, 5, and Connor Barthe, 7, were sleeping over Sunday night in the apartment. At some point during the night the snake coiled around them and squeezed them until they died.

Police said they were called to the scene at 6:30 Monday morning.

Lisa Janes, the co-owner of Little Ray's Reptile Zoo in Nova Scotia, said although she loves the animals, she knows by nature, they're unpredictable.

"We have all types of pythons and boa constrictors and we handle them on a daily basis. But we’re trained professionals and we take a lot of precautions. We’re always careful because, same as a dog or a cat, you never know what’s going to happen so you just have to be careful," she said.

Lisa Janes, co-owner of Little Ray's Reptile Zoo Nova Scotia, says, by nature, reptiles are unpredictable. (CBC)

Police are working with reptile experts, as they continue to investigate the incident.

"It’s very uncommon, where snakes don’t see humans as a food source but again accidents do happen, they’re very rare but again, if there was a feeding response triggered — maybe the snake smelled something, maybe there was a pet rat or rodent in the room or the snake just got startled," said Janes.

She said attacks such as these involving captive snakes are rare.

"There are reports, scientific reports, of more people being killed in North America by German shepherds than there are snakes, so again it is very rare but that doesn't make this incident any more unfortunate and our condolences do go out to the family," said Janes.

She said her reptile zoo will continue to educate the public on these misunderstood creatures.

"This will only make us work harder and try to teach people about what these animals are all about and what animals do and don't make good pets," said Janes.

Nova Scotia rules on large snakes

RCMP say an African rock python measured between 3.5 and 4.5 metres and weighing approximately 45 kg killed two children in Campbellton, N.B. (iStock)

There are restrictions on the types of reptiles and other exotic animals that can be kept in Nova Scotia.

Under the Nova Scotia Wildlife Act, large members of the constrictor family that exceed three metres are prohibited, including the African rock python — the species of snake RCMP say was responsible for the boys’ deaths.

But the section of the act also states that: "A Captive Wildlife Permit may be issued for the large [constrictor snakes] to people who have demonstrated understanding of proper husbandry techniques and who have appropriate facilities."

Janet Bryson, a spokesperson for the Halifax Regional Municipality, said that those zoos and museums would be considered "appropriate facilities."

The fine for being caught with a prohibited animal in Halifax is $342.

The species is the largest in Africa, sometimes growing as long as six metres.

RCMP said the Campbellton python measures between 3.5 and 4.5 metres, and weighs approximately 45 kilograms. Recent New Brunswick laws allow the sale of non-venomous snakes up to three metres long.

It's still not known how the Campbellton python escaped the store. The RCMP has launched a criminal investigation, but no charges have been laid.

Autopsies on the boys are scheduled for Tuesday