Close to 9,000 people were evacuated in northern Utah in the face of strong winds spreading a wildfire that threatened their homes and a nearby explosives factory.

The fire broke out Thursday in Kiowa Valley near Saratoga Springs, a town of some 18,000 inhabitants on the banks of Utah Lake, some 56 kilometers (35 miles) south of Salt Lake City, the MSNBC television channel said.

The flames initially burned some 750 acres of pasture but gale-force winds whipped up the blaze until it scorched some 4,000 acres, Bureau of Land Management Office spokeswoman Teresa Rigby said on the TV channel.

About 100 firefighters with helicopter support took part in the work of extinguishing the flames Friday, but as a precautionary measure the sheriff's office ordered residents to leave the area when flames spread to just 8 kilometers (5 miles) away from their houses.

Sgt. Spencer Cannon of the Utah County Sheriff's Office told The Desert News that close to 9,000 people were evacuated from their homes.

According to Saratoga Springs Mayor Mia Love, some 1,500 homes were evacuated.

Winds reached an average speed of some 32 kilometers (20 miles) per hour during the day with gusts of up to 48 kilometers (30 miles) per hour.

The firefighters still at work extinguishing the flames had managed to control 20 percent of the wildfire but lost ground due to the winds, according to Jason Curry of the Utah Division of Forestry, Fire and State Lands, who acknowledged the dimension of the challenge they are facing. EFE