DENVER (Reuters) - A wildfire burning in rugged terrain west of Denver that killed two people and left a woman missing, ignited by windblown embers from a prescribed burn, was 70 percent contained on Friday, fire officials said.

"That's the good news," incident commander Rich Harvey said of the containment figure. "The bad news is that over the weekend we're looking at the same weather conditions that started the fire in the first place."

Harvey said weather forecasters were predicting increased winds, lower humidity levels and higher temperatures over the weekend, so firefighters were aggressively attacking the fire while conditions were favorable.

The Lower North Fork Fire, which is burning through parched pine trees and grasses 20 miles west of the state's most populous city, spread rapidly on Monday after sparks from the controlled burn conducted by the Colorado State Forest Service jumped a containment line.

Flames from the blaze have torched 4,140 acres, destroyed 27 homes and an unknown number of outbuildings.

An elderly couple perished in the fire, and the search continues for a woman who has not been heard from since the blaze ignited.

"The search for Ann Appel continues, but there's nothing to report," Mark Techmeyer, spokesman for the Jefferson County Sheriff's Office, said.

Some 500 firefighters have been battling the blaze, concentrating on building containment lines and putting out scores of spot fires that have popped up in the burn area, fire officials said.

Colorado Governor John Hickenlooper this week ordered a suspension of controlled burns on state-owned lands until an investigative panel reviews the practice.

(Editing by Dan Whitcomb and Cynthia Johnston)