High temperatures, dry conditions and strong winds have fanned the flames. The worst of the blazes -- the Black Forest Fire -- had as of Tuesday destroyed more than 3,200 hectares (7,900 acres) of land near Colorado Springs.
More than 900 inmates in a correctional facility near the city, the second largest in the state, had to be transferred to another prison.
About 150 firefighters were battling the flames on Wednesday, backed up by 48 helicopters and members of the National Guard.
"This fire spread very rapidly yesterday and moved through areas very quickly and consumed a lot of land," El Paso County Sheriff Terry Maketa told a press conference Wednesday.
"Today, we're going to be focusing a lot on at least cutting some fire lines," Maketa said, adding that nearly 100 homes had been destroyed.
So far, no one had been reported missing, but the sheriff expressed concern about "those locations where people did not evacuate. One of my worst fears is that people took their chances and it may have cost them their life."
Among the other major fires threatening the state, the Royal Gorge Fire, which was less than 10 percent contained on Wednesday, had already consumed more than 1,500 hectares, according to the forest fire website Inciweb.