Up to half of the ancient Canadian town of Jasper has been burned by massive, swiftly spreading wildfires, according to officials. The fires are still out of control as firefighters work to rescue as many buildings as they can.

The fire destroyed the main town's streets in Jasper National Park in western Canada. The burned-out wreckage of cars and smoldering debris where residences once stood were captured on camera.

While no deaths have been reported, some 20,000 tourists and 5,000 residents have fled the mountainous area in Alberta province, which has been hugely popular with tourists for decades.

During a news conference on Thursday, a tearful Alberta Premier Danielle Smith struggled at times to recount the scale of the damage, but said "potentially 30 to 50 percent" of buildings had been destroyed.

"There is no denying that this is the worst nightmare for any community," she said, adding that Jasper National Park had been "a source of pride" for many generations.

Ms Smith became visibly emotional as she described the beauty of the park and its significance to the community, which relies largely on tourism. Some 2.5 million people visit the park, and nearby Banff National Park, each year.

Karyn Decore, the owner of the Maligne Lodge in Jasper, was on holiday when she learned her hotel had burned down. On Wednesday night, she received a photograph of the building in flames.

"I was horrified and devastated when I saw that photo," she told the BBC. "I think it's going to take a couple of days for the shock to wear down."

"It's really hard for everyone to comprehend that we lost one of our properties," she said, adding that she intended to rebuild the lodge.

Mike Ellis, Alberta's minister for public safety, said the fire was 5km (three miles) outside of Jasper when it was pushed by the winds to the town in "less than 30 minutes".

"Any firefighter will tell you there is little to nothing you can do when you have a wall of flames coming at you like that," he said.

"Nobody anticipated that fire to come so fast, so large and so quickly."

Justin Trudeau, Canada's prime minister, thanked the emergency services for their response to the wildfires.

"As the heartbreaking images from Jasper emerge, I want to thank the brave first responders who are in Alberta right now, fighting to save every home and every community they can," he said.

Environment Canada said there might soon be a reprieve from the hot and dry weather, which allowed the fire to grow, as rain is expected late on Thursday.

This marks another year of difficult fire conditions for the province. Last year, a record 2.2 million hectares burned in Alberta between 1 March and 31 October.

Outside Alberta, there are more than 45 active blazes in British Columbia and fires are burning in California, Oregon, Washington, Montana and Utah in the US.

The overall number of fires has decreased around the world over the last two decades.

But researchers say climate change could bring more lightning to forests in northern reaches of the globe, increasing the risk of wildfires.