An Alaskan wildfire ignited by an errant spark from a power tool has spread to 50,000 acres and burned at least 70 structures in a popular recreation area, officials said on Saturday.

The Caribou Hills fire, burning in the Kenai Peninsula south of Anchorage, had destroyed 30 homes and recreational cabins and 40 outbuildings as of Saturday, officials said. The count was expected to rise when more information was collected, said Mary Huels, information officer for the fire incident command.

About 250 firefighters from Alaska, other U.S. states and Canada were deployed to the fire, Huels said.

The fire started Tuesday in a subdivision in Ninilchik, a Cook Inlet community about a 180-mile drive southwest of Anchorage and 40 miles north of the seaside port of Homer.

"Somebody, apparently, was sharpening a shovel," Huels said.

The community has about 800 full-time residents but the area draws thousands of visitors in the summer.

Residents and tourists have been ordered out of the area but there was no official count of the people evacuated, Huels said.

Firefighters also have had trouble avoiding interference from owners of weekend cabins and others who are trying to check on the fire's damage, Huels said. Even though flight restrictions are in place, too many private planes have been buzzing the fire area, she said.

"The helicopter personnel and other people have enough hazards without worrying about private planes out there," she said.