New Bern, N.C. — U.S. Forest Service firefighters hope to soon contain a coastal wildfire that has grown to more than 20,000 acres in just three days.

The fire in the center of the 160,000-acre Croatan National Forest spread from 10,800 acres Monday night to nearly 21,250 by late Tuesday morning. It started as a prescribed burn by the Forest Service last Thursday but got out of control.

U.S. Forest Service spokesman Donald Simon said that firefighters had built a containment line around the fire that should keep it from spreading more. He said firefighters hope to knock back the flames and have the blaze under control soon.

The Croatan National Forest stretches from south of New Bern nearly to the Bogue Banks.

Forestry officials said that no one's life or private property is in danger from the fire

District ranger Pancho Smith said that crews aren't tackling the large, hot flames directly. "I don't see any sense in putting our firefighters in any danger by putting them directly on the fire line," Smith said.

Crews were using three helicopters to drop water on hot spots, ignite parts of the forest for the controlled burn and to monitor the situation. About 75 firefighters, 12 fire engines and eight tractor plows are also involved in the effort.

Air quality compromised

Thick smoke blanketed communities between New Bern and Havelock. Visibility was reduced to about a mile, and drivers were cautioned to use headlights at all times.

The fire has sent its odor as far west as Raleigh and as far north as Tarboro. More Info     'Right on cue,' temps in the 90s arrive in Triangle

The N.C. Division of Air Quality said that particle pollution in the Triangle had increased but wasn't expected to rise to unhealthy levels. Winds were expected to shift to the north Tuesday, which could mean the stench of smoke moves out of the Triangle.

Air quality officials expected Code Red conditions in Craven, Jones and Pamlico counties Tuesday and warned even healthy people to avoid extended, strenuous outdoor activity.

The state issued additional air-quality warnings for Martin, Pitt, Washington, Beaufort and Hyde counties through Tuesday evening. People who are sensitive to air pollution – the elderly, children, people who work or exercise outdoors, and those with heart and respiratory conditions – should avoid outdoor activities.