Authorities searching for fugitive teenagers Kam McLeod and Bryer Schmegelsky have more to worry about than their quarry.

The remote part of northeast Canada where their manhunt is located features dense and often barely penetrable forests, swampy areas and wild, potentially dangerous animals.

Searchers photographed a polar bear during their efforts today, and locals have also warned of black bears and wolves.

Military support has been called in to help in the hunt for McLeod and Bryer Schmegelsky, the accused killers who have been on the run in Canada's remote northeast for more than a week.

A polar bear was spotted during the search for the suspects earlier today – about 200km north of Gillam. Just some of the wildlife that can be found in northern Manitoba. pic.twitter.com/Z1hbbtOCxw

— RCMP Manitoba (@rcmpmb) July 27, 2019

Authorities believe McLeod, 19, and Schmegelsky, 18, are behind the murders of 23-year-old Australian Lucas Fowler, his 24-year-old American girlfriend Chynna Deese and 64-year-old Canadian Leonard Dyck.

Now the Canadian Air Force is becoming involved following a request from the head of the Royal Canadian Mounted Police, Brenda Lucki.

The military has provided a search and rescue CC-130H Hercules aircraft, with a crew of two pilots, an air combat systems officer, a flight engineer, a loadmaster, two search and rescue technicians and a police officer to direct the search.

"The Canadian Armed Forces are always prepared to assist other governmental organisations and the search effort around Gillam, Manitoba is another example of this co-operation," the Department of National Defence said.

The Hercules plane landed in Gillam, a town of just 1200 people in Canada's Manitoba province, just after noon on Saturday, local time.

Since Tuesday, Gillam has been at the centre of a vast manhunt involving tracker dogs, a drone, a helicopter, armoured vehicles and officers with specialised wilderness training.

Following a request from the RCMP, a Royal Canadian Air Force CC-130H Hercules & personnel arrived in Gillam earlier today to assist with the aerial search.#rcmpmb @RCAF_ARC @CFOperations pic.twitter.com/qW2PBgZdJL

— RCMP Manitoba (@rcmpmb) July 27, 2019

The brutal conditions add to the challenge of the search, but they are a problem for McLeod and Schmegelsky as well — locals say the suspects will struggle to survive for long if they are on foot and unprepared.

McLeod and Schmegelsky ended up in the area after a 3200km chase across three Canadian provinces, starting in British Columbia on the country's Pacific coast.

There were two confirmed sightings of the pair near Gillam, and later, their latest getaway vehicle was found dumped and torched there.

Vehicle checkpoints have been set up on the only road leading out of the village.

But on Friday, police admitted they couldn't rule out the possibility that McLeod and Schmegelsky had changed their appearances and slipped out, potentially with the "inadvertent" help of an unwitting resident who was "not aware of who they were".

"If anyone out there is hesitant to come forward, it is crucial for you to call police immediately," said a police spokeswoman, Corporal Julie Courchaine.

"There have been no confirmed sightings outside of the Gillam area, however we remain open to the possibility."

Despite the risk that McLeod and Scmegelsky have already escaped, the search is continuing to focus on Gillam, with police going door-to-door in an effort to finally track down the pair or at least generate new tips.

They are canvassing every home and thoroughly searching abandoned buildings.

McLeod and Schmegelsky have been charged with one count of second degree murder over the death of the Canadian man, Leonard Dyck.

No other charges have yet been laid, but police say the longtime friends are the prime suspects in the killing of Lucas Fowler and Chynna Deese as well.

Mr Fowler, from Sydney, and Ms Deese, from Charlotte in North Carolina, had been travelling through northern British Columbia en route to Alaska when they were found shot to death alongside their blue Chevrolet mini-van on July 15.

On July 19 Mr Dyck, a University of British Columbia lecturer, was found dead near Lake Dease, two kilometres from the teens' burnt-out Dodge and almost 500km from where Mr Fowler and Ms Deese's bodies were discovered.

Investigators have warned the public to consider McLeod and Schmegelsky "armed and dangerous".

Ms Deese's brother, British Deese, told news.com.au the ordeal was taking a huge toll on his family.

Mr Deese said his family was "worn out" trying to come to terms with the tragic loss of his sister.

"We didn't expect that this would get to much international attention but it's oddly comforting to have the world mourning with you," Mr Deese said.

The hunt for the killers moved to Gillam after police confirmed two sightings of the suspects in the area.

The development came as a shock to many locals, who are so used to living in a safe community that many don't even lock their doors.

One local woman said the community was "freaking out".

"We're not used to this — nobody locks their door," she told CBC.

Another local, Mario Catalano who managed a fuel service company in town, told the media that some people had even resorted to sleeping with their guns.

"Everybody in the community is, I guess I wouldn't say paranoid … nervous, scared," he said.

"I've heard people are sleeping with their guns close."

Local stores, bars and restaurants have reportedly been closing early so no one has to walk home in the dark.

Meanwhile, a former classmate of Schmegelsky has claimed he has a history of making disturbing and violent comments.

Madison Hempsted, who shared a class with Schmegelsky when they were both 13, revealed that history to Global News.

A Hercules plane has been brought in to help the search. Photo / Twitter

The teen said she and her friends didn't speak with Schmegelsky very often, but when they did, he would allegedly turn the conversation towards different methods of murder.

"I don't want to be rude, but he was kind of a weird kid," she said.

"He didn't really talk to anyone, super into himself. But when he did talk to people, the things he said were kind of scary. All he ever said to me was how he wanted to kill me and ways he would do it."

One of her friends has claimed they had heard the accused say he wanted to kill his whole family.

Ms Hempsted said some of the scenarios he would allegedly bring up were "pretty detailed".

"He would say things about how he would cut our heads off and then he would take a gun and put it in his mouth and shoot himself in front of us," she said.

She told the media outlet that, while his comments were disturbing, she didn't really think much of it until now.

"He didn't have very many friends," she said.

"We thought he was trying to be funny and make people laugh and make friends, because he was so quiet."

Schmegelsky's father Alan said his son bought a black suit with his second pay cheque from the Walmart where he worked this year and told him he was heading to Alberta with McLeod to look for jobs.

In the ongoing search for the suspects, RCMP officers have started to canvass every home in Gillam & Fox Lake Cree Nation. In addition to the canvass, they are also thoroughly searching every abandoned home in the area – over 100 cleared so far. #rcmpmb pic.twitter.com/SdQhyqxJrn

— RCMP Manitoba (@rcmpmb) July 27, 2019

"I was absolutely flabbergasted to learn two days later … that they were up in the Yukon," he told reporters.

"Now I realise it's his funeral suit."

On Monday, Mr Schmegelsky revealed Bryer had told him he and McLeod had been "training in war" in the woods for more than two years and were masters of camouflage.

He described his son's upbringing as being troubled, with his parents going through a bitter separation in 2005.

The boy, then aged five, moved with his mother to the small Vancouver Island community of Port Alberni, where he met McLeod. They attended the same elementary school and quickly became inseparable best friends.

Mr Schmegelsky said his son was on a "suicide mission" and he expected he would be killed by police within 48 hours.

"He wants his hurt to end," Mr Schmegelsky told Canadian Press.

"They're going to go out in a blaze of glory.

"Trust me on this."