DENVER?Eight people were reported missing Wednesday as firefighters battled for a third day to contain a major wildfire in the western US state of Colorado, officials said.

The blaze, which erupted Monday in Fourmile Canyon northwest of the state capital Denver, did not grow overnight but extended over some 2,800 hectares (7,000 acres), said Boulder County Sheriff Commander Rick Brough.

Local TV showed pictures of houses going up in flames. Brough said the fire has so far destroyed 92 structures, although it is not known how many of these are homes.

Authorities have located 12 of 20 people initially reported missing, but expect the number still unaccounted for to grow, as deputies contact relatives in an attempt to locate missing residents of the mountainous area.

"We also send people up to the residences to check for them," Brough said.

It was unclear whether those missing are affected by the blaze, or are simply unaccounted for because they could not be contacted.

More than 200 firefighters, 24 fire engines and nine aircraft were fighting the fire and more resources are coming in, said Laura McConnell with the Boulder County Incident Management Team.

Federal emergency management officials issued a Type I, or national priority, fire designation.

Colorado Governor Bill Ritter has pledged $5 million in state funds to help fight the blaze.

Officials hope improving weather conditions Wednesday, with higher humidity, lower winds and a chance of thunderstorms in the area, will assist firefighters.

A huge plume of smoke was visible in Denver, 65 kilometers (40 miles) to the southeast.