Two lightning-sparked fires were burning in forests of western Colorado Friday and firefighters were ramping up efforts to suppress flames.

Clouds and rain Thursday afternoon helped slow the largest fire, dubbed the Lowline fire, which was burning on 803 acres of mostly public land managed by the U.S. Forest Service about 14 miles north of Gunnison. Smoke plumes rose from a ridge, at an elevation of 9,400 feet, between Squirrel and Mill creeks. The fire was burning spruce and aspen in forests laden with dead and fallen trees.

Federal fire managers on Friday said hot weather will favor the flames.

“We expect this fire to build some intensity again, though not necessarily making big runs,” said Rick Barton, spokesperson for the interagency team fighting the fire. “We are in full suppression mode.”

No injuries or damage to buildings were reported.

Ground crews were using bulldozers to try to create breaks around the fire, Barton said. Three helicopters hauled large buckets of water for dousing flames. Gunnison County authorities have evacuated residents of ten homes along County Road 818. Other residents of about 40 homes have been told to be ready to evacuate.

Elsewhere around Colorado, a Thunder fire southwest of Norwood had burned across five acres, authorities estimated Friday morning, mostly on private property.

San Miguel County Sheriff officials said in a posting on Twitter that hot, dry and windy conditions Friday may lead to erratic fire activity. Firefighters deployed an aerial drone carrying an infrared camera to monitor hot spots. This fire was not threatening people or buildings, officials said, but residents in the area have been advised to be ready to evacuate if necessary.

A fire earlier this week that burned across 14 acres west of Colorado Springs in Teller County, near the Florrissant Fossil Beds National Monument, has been contained.