Firefighters say a wildfire burning on an estimated 640 acres in northern Colorado is 5 percent contained.
Fire officials said Tuesday that the blaze northwest of Fort Collins has grown as temperatures rise and the humidity drops, but it is growing in a direction away from homes.
Fire spokeswoman Reghan Cloudman says calls were made to 160 phone numbers telling residents to prepare to leave, just in case.
Cloudman says the fire is within a quarter mile of some homes.
The fire is believed to have been human-caused, but investigators haven't determined if it was intentional.
In western Colorado, firefighters expected to have a 170-acre fire between Delta and Whitewater fully contained sometime Friday. It was 80 percent contained Tuesday. That fire was started by lightning. No structures are threatened.