By Melissa Gray, CNN
(CNN) -- Dry and hot conditions allowed a spate of wildfires to burn across Colorado on Sunday, forcing thousands of people into shelters and cutting off access to some of the state's largest national forests.
Some 11,000 people were evacuated in and around Colorado Springs after the 2,000-acre Waldo Canyon Fire began there Saturday. The entire nearby city of Manitou Springs was empty, Mayor Marc Snyder said.
The Waldo Canyon Fire was 0% contained Sunday.
The Federal Emergency Management Agency authorized the use of federal funds to help fight the Waldo Canyon Fire after Colorado Springs and surrounding El Paso County declared an emergency, which allows them to receive state and federal aid.
"This is obviously beyond the resources of any one agency," Colorado Springs Mayor Steve Bach said. "This declaration is the next step needed for an incident of this size."
More than 70 firefighters were holding the line west of Colorado Springs, said Sunny Smaldino, spokeswoman for the city's fire department.
Six other wildfires were active in the state, according to the Colorado Division of Emergency Management.
Colorado Gov. John Hickenlooper, who traveled to the Waldo Canyon Fire on Sunday, said 70 helicopters and tankers were in the air over Colorado to help crews battle the flames.
"Almost half the airborne fire suppression in the country is in Colorado," the governor said. "We recognize this is going to take a big push."
The largest of the fires was the High Park Fire, which began June 9 and has now consumed 83,205 acres, the U.S. Forest Service said. It was 45% contained Sunday.
Nearly 2,000 fire personnel were fighting the wildfire, located in the Arapaho and Roosevelt National Forests, and more were expected later, emergency management spokeswoman Micki Trost said.
She said the High Park Fire has destroyed 191 homes, though officials expect that number to go up once crews are able to go in and assess the damage.
Gene Ellisberg was shooting pictures in the nearby Rocky Mountain National Park when he saw "a giant, enormous smoke cloud" about 30 to 50 miles away, he told CNN.
Ellisberg lives in the flatlands near Denver, but said, "I'm close enough to the fire that when the wind blows, it makes the air quality horrible."
The other major fire was the 19,566-acre Little Sand Fire, burning on rugged, inaccessible terrain in the San Juan National Forest in southern Colorado. It was 31% contained Sunday.
Though smaller than the other wildfires, the Waldo Canyon Fire was of big concern because of its aggressive behavior, officials said.
"I don't think there's been anything more devastating than that fire right there," El Paso County Sheriff Terry Maketa said, adding the fire has been spreading in two or three different directions.
"This is the greatest natural threat that we've seen in this community in the last 30 or 40 years," Maketa said.
Kimberly Shumard, 47, who lives 20 miles from the fire, said the air can be thick and full of ash. She said she woke up to burned leaves in her yard Sunday and can hear fire-fighting planes and helicopters overhead.
"This is the scariest thing I've seen, because it's so unpredictable," Shumard told CNN.
She described the smell as "stronger than a campfire." She said her dog, a Shepherd-Lab mix named Pasha, is keeping a close eye on where she and her husband are at all times and staying close by.
Also Sunday, FEMA authorized federal funds to help fight the Weber Fire in southwest Colorado, which stood at 6,500 acres Sunday and 0% containment.
"Weather conditions are ripe for the fires," Trost said. Temperatures have been above 100 degrees Fahrenheit in the past two days and humidity has been low, she said.
For firefighters, that means a danger of overheating and a need to keep them hydrated.
The fires are prompting a long list of ever-changing road closures. County and state officials and charities such as the Red Cross and Humane Society are using Twitter and other social media to keep residents updated.
The use of Twitter is beneficial to emergency management officials as well, she said, because it allows residents to share photographs and details of what they're seeing.
Trost encouraged residents to heed evacuation warnings as soon as they're issued.
"When you receive that call to evacuate, (make sure) that you are ready to go and that you get out of the area as quickly as possible for your safety and so the fire crews can get into the area," Trost said.