Crews planned to continue setting "burnout" fires Thursday to try containing a wildfire that had burned 7,500 acres near Patagonia, a federal fire information service reported.

The Soldier Basin Fire, six miles south of Patagonia and five miles east of the Nogales airport, was burning in steep terrain on Coronado National Forest land, the Incident Information System website reported.

"Fire personnel plan to continue burnout operations along the north and north east flanks to tie the main body of the fire in with prepared lines," the report said. "Area residents should expect to see continued fire growth and smoke as firefighters continue aerial ignitions over the next 4-5 days."

After the fire raced north Wednesday, afternoon, aerial tankers were called in for retardant drops that succeeded in slowing it, the report said. Area residents were being cautioned that while no structures were threatened, the fire's movement remained unpredictable.

The fire started last Friday night and was human caused, officials said. It is the first significant blaze in Southern Arizona this season.