UPDATE: July 16 3:30 p.m.
The Pine Creek Fire has now grown to an estimated 1,200 acres and is only 10 percent contained.
Firefighters spent much of the day Tuesday burning out fuels along Wildcat Gulch Road, progressing in a southern direction from high elevation downward.
Grimes Creek Road remains closed at Highway 21, because of dangers of rolling rocks and falling logs. Fire managers say they are making every effort to open the road as soon as it is safe to do so.
Approximately 260 fire personnel are working the fire lines, including nine 20-person hand crews, 9 engines, one dozer and air support.
Travelers along Highway 21 are still cautioned to the possibility of heavy smoke on the highway.
The cause of the Pine Creek Fire remains under investigation, but it is believed to be human-caused.
ORIGINAL POST: July 16 9 a.m.
200 additional firefighters have been dispatched to the Pine Creek Fire burning about 15 miles northeast of Boise and four miles east of Shafer Butte. The fire has already scorched 800 acres north of Highway 21.
Motorists on Highway 21 are being cautioned, due to periods of thick smoke.
Boise County officials have closed Grime Creek Road past the junction to the Clear Creek Subdivision, but residents of the subdivision are still granted access to their homes. No structures have been threatened.
Thus far, fire resources include seven 20-person hand crews, two hotshot crews, 12 engines, two dozers and three helicopters.
Fire officials say they'll spend much of July 16 building fire lines to secure the line along the Wildcat Gulch Road. The fire burned actively throughout the night of July 15, but there was limited perimeter growth.
Weather forecasts have called for lightning in the area today, so fire managers are bracing for additional fire starts.
Firefighters from the Clear Creek, Valley of the Pines, Wilderness Ranch and Idaho City volunteer fire departments are on the line, along with resources and personnel from the U.S. Forest Service, Bureau of Land Management and the Idaho Department of Lands.
The fire is in the IDL Southwest Forest Protective District.