Glacier National Park has temporarily closed the Granite Park area and trails leading to it because of grizzly bear activity.

The Highline, Loop, and Swiftcurrent trail (from Swiftcurrent Pass to Granite Park Chalet) are all closed as of Sunday evening, meaning that access to the Granite Park area is not possible, the Park said in a release.

Park staff who live in the Granite Park area have been monitoring grizzly bears frequenting the area and on Sunday received several first hand visitor reports of encounters with a bear or bears along the trail within the general area of the campground and the chalet. The bear or bears exhibited behavior consistent with being disturbed and frustrated by human presence. Bears can respond aggressively in defense of themselves, a food source, or cubs, the Park said.

On Monday morning, park staff were set to hike to the area to observe bear behavior and conduct hazing activities as appropriate.

The Granite Park backcountry campground will be closed to campers arriving Monday.

Hundreds of people hike those three trails on a daily during the summer months, as Granite Park is one of the most popular backcountry destinations in Glacier.

The park expects that the trails will be closed at minimum until park staff can evaluate the area on Monday, and may be closed an indeterminate period of time afterwards, depending on their findings.

Guests planning to hike to Granite Park Chalet with reservations for Monday night should call the Granite Park Chalet Office at 888-345-2649 for more information and updates. The park did not expect that any trail status updates will be available before Monday afternoon.

People currently in the Granite Park region departing Monday morning were being permitted to hike out the Loop or Swiftcurrent Pass Trails, but not the Highline Trail.

People can monitor trail status by visiting the park’s Trail Status webpage.