Colorado ? A Colorado wildfire that has destroyed 170 homes showed no signs of relenting Thursday as wind gusts of more than 40 mph fueled fears that the flames would move east from the Rocky Mountain foothills and into the heart of Boulder, where some residents were warned to be ready to flee.

Officials worried about a repeat of the devastation in the foothills, where neighborhoods once filled with million-dollar homes and scenic mountain cabins have become piles of smoking rubble.

Authorities told residents on the west side of Boulder to be prepared to evacuate if the wildfire moves into town.

The reported loss of homes surpasses that of the 2002 Hayman fire in southern Colorado, the most destructive in state history. It destroyed 133 homes and 466 outbuildings on 138,000 acres of more sparsely populated area.