By Steve Quinn
JUNEAU, Alaska (Reuters) - A fast-spreading Alaska wildfire has destroyed up to 45 homes and forced authorities to restrict traffic on a major highway connecting two of the state's largest cities, state officials said on Monday.
As many as 200 firefighters have been battling the 6,500-acre fire with more specially trained teams en route from the Lower 48 states, Alaska Forestry Division spokesman Sam Harrel said.
Crews have been attacking the fire on the ground and by air, getting help from the three Alaska National Guard Blackhawk helicopters, according to state reports.
Harrel said the fire was ignited by human activity but the specific cause remains under investigation. Dry and warm weather accelerated the blaze, he said.
The fire started early on Sunday afternoon near Willow, about 40 miles north of Anchorage and where the Iditarod, Alaska's famed sled-dog race, typically kicks off.
It initially covered about two acres, but within 11 hours had ballooned to 6,500 acres, according to the forestry division reports. Harrel said flames quickly jumped from one 30- to 40-foot spruce tree to the next, forcing a temporary closure of the Parks Highway, which links Anchorage in the state's south central region to Fairbanks in Alaska's eastern interior.
Residents along a 14-mile stretch have been evacuated.
By Monday morning, portions of the road re-opened to single-lane traffic with vehicles needing a pilot car to guide them, Harrel said. The highway remains subject to intermittent closures, Harrel said.
As of Monday morning, Harrel said about 25 primary homes had been destroyed and as many as 20 secondary residences were also lost.
There are about 170 residential structures in the evacuation area, according to the Matanuska-Susitna Borough. These homes range from year-round residences to seasonal cabins, said borough spokeswoman Patty Sullivan.
The borough also reported more than 200 people checking into evacuation centers, including residents and tourists, Sullivan said.
(Editing by Cynthia Johnston and Sandra Maler)