By Emmett Berg
KALISPELL, Mont. (Reuters) - Flames roared unchecked through heavy timber for a third day in Montana's Glacier National Park, where the main road has been closed through the eastern half of the park, along with two campgrounds and several trails right at the height of the summer travel season.
Marking the first major wildfire to hit Glacier in nearly a decade, the blaze has charred roughly 4,000 acres since igniting on Tuesday near a popular hiking spot, Logan Pass, and continued as of Thursday to defy firefighters' attempts to contain it, officials said.
A group of hikers initially feared to have been in harm's way returned safely, the National Park Service said.
No injuries have been reported and the only structure lost so far was the historic Baring Creek Cabin, said Katelyn Liming, a fire management spokeswoman. The cause of the blaze is unknown, she said.
The Park Service said it planned to reinforce ground crews and aerial firefighting teams on Thursday as forecasts called for strong winds possibly picking up during the day.
Heavy winds helped the blaze double in size between Tuesday and late Wednesday, but there was little growth in the fire zone overnight, Liming said.
The fire's impact was limited so far to the eastern side of the park. The picturesque Going-to-the-Sun Road, which bisects Glacier and crosses the Continental Divide, remained shut down for about 20 miles (32 km) from the main entrance to the park's center.
The Rising Sun Campground and Motor Inn also were closed to the public, as well as the St. Mary Campground and several trails, including much of the popular Highline Trail.
The rest of the park, occupying over 1 million acres in northwestern Montana and straddling the Canadian border, remained open to the public.
Authorities were evacuating homes along the banks of Lower St. Mary Lake just outside the park as a precaution.
Liming said the last major wildfire in Glacier came in 2006, when when flames scorched more than 34,000 acres of the park and Blackfeet tribal land.
The park, named for the glaciers that sculpted its landscape millions of years ago and have been rapidly receding, draws more than two million visitors a year, with July accounting for the biggest monthly share of park admissions.
Liming said she was unable quantify the impact of the latest fire on visitation. "There are still lots of people here," she said.
(Writing by Victoria Cavaliere; editing by Hugh Lawson)