Firefighters and soldiers worked to stamp out hundreds of wildfires raging across western Canada that are threatening thousands of people and triggering air quality warnings across the country and in the U.S. West and Midwest, authorities said.

Steve Roberts, a Saskatchewan wildfire management official, said better visibility has allowed aircraft to dump water on the flames there. Several hundred Canadian soldiers were involved in firefighting efforts and the military said another 500 troops from Manitoba were on standby. Fire-fighting crews from across Canada and from South Dakota have been helping out.

But even as progress was being made in Saskatchewan, wildfires burned in parts of British Columbia and northern Alberta and authorities were forced to seek help from around the country and other countries, including Mexico and Australia.

"As we started down the road with these fires, Alberta and British Columbia fire hazards escalated, the numbers of fires increased and they had community evacuations as well," Roberts said. "That has stretched the availability of resources across the country."

Karen Hill, a spokeswoman for Saskatchewan's provincial emergency services, said an estimated 10,000 to 12,000 people in the province have been forced to leave their homes in recent days. The evacuations are mostly from more than 50 communities in the northern part of the province.

The Canadian Interagency Forest Fire Centre, which co-ordinates firefighting services for the provinces and territories, said Canada may have to seek more help from the U.S. and abroad.

The latest report on the agency website said the wildfire hazard is extreme and major wildfires "have the potential to exhaust agency fire resources nationally."

Alberta said Wednesday that it was bringing in 62 firefighters from Mexico to help battle 92 wildfires burning in the province, including 33 listed as out of control.

British Columbia, with more than 180 fires, was bringing in crews from Australia.

Environment Canada continued to issue special air quality advisories for parts of British Columbia, Saskatchewan, Manitoba and northwest Ontario due to wildfire smoke.

Smoke from the wildfires has also led to air quality advisories in the U.S., including Washington state, North and South Dakota and Colorado.

Wildfire expert Mike Flannigan said tinderbox conditions in the Western provinces set the stage for the wildfires. "Our weather this year has been very hot, dry and windy," said the University of Alberta professor.

"This is consistent with what we expect with climate change. I'm not saying every year is going to be a bad fire year, but we are going to see a lot more fire on the landscape."

Kerry Anderson, a research scientist with the Canadian Forest Service, said the weather pattern known as El Nino, which is caused by the warming of the Pacific Ocean off the coast of South America, is responsible.

He expects weather conditions will settle down in Saskatchewan in the coming weeks, but warmer than normal temperatures will likely persist for a while in B.C. and Alberta.

Anderson said even if crews bring the Saskatchewan fires under control, they may not actually be put out until the fall.

"The large fires that are burning there will continue to burn until they are contained or until a fire-ending event may occur, and that may just end up being the first snowfall."

___

Associated Press writer Charmaine Noronha in Toronto contributed to this report.