The Reynolds Creek Fire continues to burn out of control in Glacier National Park. This image was taken Tuesday night/NPS

Gusting winds are challenging more than 300 firefighters as they try to get a hand on a wildfire in Glacier National Park that has closed roughly half of the Going-to-the-Sun Road and forced evacuations of a lodge and campground on the eastern side of the park.

Smoky conditions have made it difficult for fire bosses to get an accurate measurement of the Reynolds Creek Fire, which has been estimated at 4,000 acres in size. However, winds led to some spotting that touched off a fire of undetermined size on the southern shore of St. Mary Lake. The National Weather Service was calling for more gusty winds Friday afternoon that could lead to "extreme fire behavior and the potential for significant fire growth.

Aiding the firefighters on the ground were six helicopters to provide water drops, though as of midday Friday no fixed-wing planes capable of dropping thousands of gallons of fire retardant had been called in.

The fire, spotted Tuesday afternoon about six miles east of Logan Pass, has led to closure of the Rising Sun Motor Inn, the Rising Sun Campground, and the St. Mary Campground. The park's visitor center at St. Mary was closed to the public so it could be used as a staging area for firefighters. Authorities also have called for the evacuation of the west side of Lower St. Mary Lake and were evaluating whether to evacuate the east shore of Lower St. Mary Lake.

The townsite of St. Mary also was being evaluated for possible evacuation.