ANCHORAGE, Alaska — A wildfire north of Anchorage shut down a key highway and forced the evacuation of 1,700 homes after it mushroomed in size.

The human-caused blaze was reported at just 2 acres Sunday afternoon and had burned through more than 10 square miles by early Monday, officials said. It chewed through forest and brush around Willow, in the Matanuska-Susitna Borough about 40 miles from Anchorage.

"It's got a little wind behind, it has a lot of fuel and it's grown," said Tim Mowry, spokesman for the Alaska Interagency Coordination Center.

Evacuations grew along with the blaze: Officials first reported residents of 10 homes fleeing, then 20. Mowry said in a statement early Monday that the fire forced the evacuation of 1,700 residential structures in the Willow area.

More than 2,000 rural residents are spread along about 20 miles of the Parks Highway, which was closed.

Even an evacuation center had to be evacuated. Emergency officials set up the shelter at a community center on the highway, but news reports said later that the people there were sent to a middle school.

About 210 residents signed in at two evacuation centers, authorities say.

One firefighter was treated for heat exhaustion, Matanuska-Susitna Borough spokeswoman Patty Sullivan said. No additional details were released.

Borough Emergency Manager Casey Cook estimated that 10-15 structures had burned, The Alaska Dispatch News reported.

The fire jumped to both sides of Parks Highway and was moving south, Mowry said, but firefighters were expecting that its growth would slow with higher humidity.

People started the blaze, but Mowry did not have additional details.

The blaze has been dubbed the Sockeye Fire for the avenue in Willow where it started and where homes were evacuated quickly after it was reported. The response was swift and strong because of the fire's proximity to homes.

"We're throwing everything we can at it at this point," Mowry said.

Tankers unloaded retardant, and a helicopter dropped loads of water as more aircraft planned to join the fight. Nearly 200 personnel were battling the blaze and more expected, Sullivan said.

Associated Press writer Bob Seavey contributed to this report.