A fire burning south of La Junta in the Comanche National Grasslands grew to 400 acres from about 300 acres, fire managers said. The blaze, believed to be started by lightning Monday, threatened six buildings, including some on a historic ranch, said Larry Helmerick of the interagency Rocky Mountain Coordination Center.
Geologists working in the area had to leave Tuesday.
About 70 firefighters, including a Forest Service hot shot team, three single-engine tankers and a helicopter were helping battle the blaze, which was 40 percent contained.
The planes and helicopter were concentrating on two hot spots of about 20 acres each, said Tom Peters, district ranger of the grasslands.
``It's terribly dry down there. We have to be careful because there is a lot of dry land and lightning that is hitting all across southeast Colorado and fires can spark up fast,'' Peters said.
Lighting was blamed for a wildfire that erupted June 3 west of Meeker in northwestern Colorado. Fire officials said the blaze had grown to 2,500 acres in sagebrush and pinon-juniper trees on Bureau of Land Management land.
Crews were letting the fire burn in spots to clear dead vegetation and improve wildlife habitat. No structures were in danger.
A number of Colorado counties have already instituted fire bans.
``Whether it's a cigarette, or something else accidental, or burning permits that get out of hand, any of that stuff,'' Gypsum Fire Chief Dave Vroman said. ``It's extreme fire danger.''
The western half of the state and the south-central plains were under a red flag warning Wednesday, meaning the fire risk was high. Lightning and winds were expected throughout the area.
``We're not looking forward to that,'' Helmerick said.
The fear is the trees and grass may soon be as dry as in 2002, one of Colorado's most destructive fire seasons.
``I've talked to firefighters in the last week who said the mountain grass is green, but it will quickly cure and brown without rain in the next week or so,'' said Barbara Timock, spokeswoman for the Pike and San Isabel national forests.
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