A wildfire that ignited Saturday afternoon near the National Center for Atmospheric Research prompted the evacuation of homes in a large area of south Boulder, including the Table Mesa neighborhood and Eldorado Springs and Sans Souci.
At least 19,000 people were ordered to flee about 8,000 homes.
By Sunday morning the fire had burned about 200 acres but was 21% contained. No structures were damaged or destroyed.
MORE: See the latest evacuation map here.
Authorities said at about 4 p.m. Saturday, about an hour after the fire ignited, that the fire was moving southeast and burning on about 20 acres. By 5 p.m., the fire’s size was estimated at 60 acres with no containment. By 5:30 p.m., the fire’s size was estimated at 123 acres.
But by Saturday night winds had died down and some evacuees were allowed to return to their homes.
Eldorado Canyon State Park was closed because of the fire, which was burning amid warm temperatures and gusty winds.
Images from the scene showed smoke rising near the Flatirons.
Authorities are investigating what sparked the blaze, named the NCAR fire.
The wildfire comes about three months after the Marshall fire swept across Boulder County, killing two people and destroying roughly 1,000 homes.