One of two wildfires threatening the town of Jasper in the Canadian Rockies’ largest national park has roared into town and started burning buildings.

Jasper National Park officials said the fire entered the southern edge of the community on Wednesday evening and crews were battling multiple structural fires and working to protect key infrastructure.

There were significant losses in some areas, they said.

Forest firefighters and others without self-contained breathing apparatus were told to evacuate to the nearby town of Hinton, with structural firefighters staying behind.

Parks Canada spokesperson James Eastham told reporters outside Jasper that the town is filled with smoke and there “has been structural loss”.

“At this point I can’t confirm how many locations or specific structures. The fire continues to burn,” he said.

Parks Canada said firefighters are working to save “as many structures as possible and to protect critical infrastructure, including the wastewater treatment plant, communications facilities, the Trans Mountain Pipeline and others”.

A few hours earlier, many first responders were ordered out of Jasper National Park for their safety.

Jasper is being threatened by fires from the north and south, and the town’s 5,000 residents – along with 20,000 park visitors – fled on short notice late on Monday when the fires flared up.

Prime Minister Justin Trudeau said officials are “mobilising every necessary resource available”. Alberta premier Danielle Smith said she was “heartbroken”.

A record number of wildfires last year forced more than 235,000 people across Canada to evacuate and sent thick smoke into parts of the US, leading to hazy skies and health advisories in multiple US cities.

The northern fire was spotted three miles from Jasper earlier in the day. The southern fire had been reported five miles away from the town, but Katie Ellsworth of Parks Canada said strong wind gusts sent it racing.

She said bucketing efforts by helicopter failed, crews using heavy equipment to build fireguards could not complete the work before having to pull out, and water bombers could not help due to dangerous flying conditions.

A last-ditch effort to use controlled burns to reroute the fire to natural barriers like Highway 16 and the Athabasca River failed due to “unfavourable conditions”.

The hope was that rain forecast overnight would bring some relief.

Ms Ellsworth said the decision to relocate all first responders to Hinton, just outside the eastern edge of the park, “has not been made lightly”.

She said: “Given the intensity of fire behaviour being observed the decision has been made to limit the number of responders exposed to this risk.”Jasper National Park is considered a national treasure. The United Nations designated the parks that make up the Canadian Rockies a World Heritage Site in 1984 for the striking mountain landscape.

In 1953, Hollywood star Marilyn Monroe visited to make the movie River Of No Return. More recently, TV show The Bachelorette was filmed there.

Park rangers in helicopters scoured the park earlier on Wednesday looking for stragglers still there despite a mass evacuation aimed at moving visitors and residents away.

Searchers looking through the remote trails of Jasper National Park had already picked up 245 people, and they continued the search on Wednesday in two helicopters, Ms Ellsworth said.

Residents and visitors streamed out by the thousands late on Monday and Tuesday, and officials said on Wednesday that the evacuation of the town of Jasper was complete.

Ms Ellsworth said park officials expected the evacuation of the park’s backcountry areas to be completed later on Wednesday. Reservations are required for the park, so authorities have an idea where people are, but Ms Ellsworth said she was not sure how many people were left.

Alberta has been baking in scorching temperatures that have already forced another 7,500 people out of remote communities. About 177 wildfires were burning across the province.