Nearly 4,000 people have been forced from their homes in northwestern Ontario as emergency services workers struggle to get a handle on raging forest fires that have already burned through 3,000 square kilometres of land.

Officials ordered 1,800 First Nations residents out of their homes earlier Wednesday, and another 500 were airlifted throughout the day from the communities of Sandy Lake and Kingfisher Lake.

Officials said 112 active fires and the resulting thick smoke have moved dangerously close to a number of communities.

"While the number of fires we've had in Ontario this year is about the same as last year, the magnitude and the complexity of these fires is much greater," Ontario Natural Resources Minister Linda Jeffrey said during a news conference.

"To date, the area burned is 300,000 hectares. That's almost five times the average."

Fires are within three kilometres of structures on Keewaywin First Nation and within 10 km of Sandy Lake First Nation.

All residents of Keewaywin and Cat Lake First Nations are already out of their homes.

Residents are being flown to Thunder Bay and then sent to evacuation centres scattered throughout the region, including in Greenstone, Dryden and Sioux Lookout. They could be out of their homes for at least two weeks.

Hundreds of Canadian Forces personnel are helping with the evacuation efforts, in addition to aircraft from bases across the country.

"As forest fires continue to ravage many parts of Northern Ontario, it's reassuring to know that members of the Canadian Forces are ready to respond quickly to help endangered Canadians when they are called upon to aid the provincial and municipal governments," Defence Minister Peter MacKay said in a statement.

More Canadian Forces evacuation flights are planned for Thursday, the military said.

About 2,000 firefighters are battling the blazes, a quarter of which are from outside the province. More than 100 firefighting aircraft are also trying to douse the flames.

Tony Clement, minister for the federal economic development initiative for northern Ontario, visited displaced residents and volunteers at an evacuation centre in Dryden.

"Obviously they're a bit disoriented, but given the circumstances they're faring OK," Clement said.

"A lot of these fires are in very remote areas. They can change direction with one gust and they can leap over various areas and be quite threatening ... so this a real challenge."

Stan Beardy, Grand Chief for the Nishnawbe Aski Nation, as well as the Chiefs of Ontario and the Assembly of First Nations, urged the government to declare a state of emergency so more resources could be directed to the firefighting and evacuation efforts.

"We've never seen forest fires this bad," said Beardy. "We're not talking about one or two big fires, we're talking about 100 fires that are out of control in many cases."

Many of the communities are not accessible by road, and Beardy fears that aircraft used in evacuation efforts will soon be unable to fly, leaving residents stranded.

Clement said the provincial government would first have to declare a state of emergency before the federal government could step in with additional resources.

With files from The Canadian Press