Firefighters labored Thursday to protect hundreds of homes from a wind-whipped wildfire that had more than doubled in size in 24 hours.

U.S. Forest Service officials said 1,800 acres of grass, brush and ponderosa pine had burned near Bailey, a town of about 4,400 people in the foothills 35 miles southwest of Denver. Only about 10 percent of the blaze was contained as of Thursday morning.

''We just can't be very aggressive with this fire right now. We just don't have enough crews and air power,'' fire information officer Dave Steinke said.

About 200 firefighters battled overnight to protect homes, schools and other buildings. No homes were destroyed, but a barn and a shed burned Wednesday, officials said. More firefighters were bring brought in Thursday, as well as two larger helicopters and more air tankers.

''Today is the first day to really attack the fire and try to gain some control,'' Steinke said.

The entire town was evacuated Wednesday afternoon and four schools were closed when flames crept to within a quarter-mile of downtown.

Most residents were allowed back in their homes by nightfall when cooler weather eased the fire threat, but the sheriff's department said many areas were without electricity or water. About 400 people were unable to return home.

The fire started Tuesday in an area popular with smokers, and Park County Sheriff Fred Wegener said some teens have been questioned. No arrests have been made, he said.

Weary residents watched Wednesday as smoke billowed above ridges near their homes.