COLORADO SPRINGS, Colo. (AP) — Authorities say it remains too dangerous for them to fully assess the damage from a destructive wildfire threatening Colorado's second-largest city.

Colorado Springs emergency management director Brett Waters said Wednesday morning that officials don't know how many houses have been destroyed in the blaze that has forced mandatory evacuations for more than 32,000 residents.

The fire is nowhere near contained, but incident commander Rich Harvey says firefighters have been able to establish and maintain a line of protection in some areas.

Fire information officer Rob Dyerberg says the blaze doubled in size to about 24 square miles overnight Tuesday into Wednesday.

Thunderstorms are expected in the afternoon, but Harvey says they could bring unpredictable winds that would hinder firefighters' efforts near the city of 419,000 people.