A windblown wildfire that already has destroyed more than 300 mountaintop homes pushed into a previously untouched subdivision, burning five cabins and threatening 60 others, a fire official said Saturday.

The human-caused fire began on June 17 and destroyed 317 homes last month in and around the vacation hamlet of Summerhaven on Mount Lemmon. It was about 55 percent contained.

The fire has now burned 68,000 acres and has cost in excess of $10 to fight so far. It is listed as 55% contained.