Firefighters expect to contain an 850-acre blaze by Friday that has blackened oak, brush and Ponderosa pine in Zion National Park, officials said.

Park Superintendent Harry Grafe said up to 200 firefighters had been fighting the blaze.Meantime, 45 firefighters battled a 3,500-acre fire of unknown cause that broke out late Wednesday on Bureau of Land Management and private land about three miles north of Beryl, Iron County. Officials said the fire was 85 percent contained and crews anticipated full containment by 3 p.m. Thursday, said spokeswoman Eulail Pickering.

The Zion fire began June 19 and was allowed to burn in a small "conditional area" in accordance with park policy allowing natural fires to take their course, said Chief Ranger Bob Andrew.

On Sunday, however, winds gusting to 60 mph fanned the flames out of the conditional area, and fire crews were brought in, he said.

Winds dropped to 10 mph Wednesday, and Andrew said fire officials predicted containment by 6 p.m. Thursday.

No injuries or property damage were reported in the fire in mountainous terrain about 11/2 miles southeast of Lava Point near the West Rim Trial, Andrew said.