Great Smoky Mountains National Park has temporarily closed some trails due to "aggressive bear activity," and advised visitors to remain alert during their time in the park.

Ramsey Cascades Trail remained closed as of May 13 after being temporarily sealed to the public May 8 due to bear activity, according to an alert on the National Park Service website. Mollies Ridge shelter in Townsend along the Appalachian Trail also remains closed because of aggressive bears, Knoxville News Sentinel, part of the USA TODAY Network, reported.

The park also notes that high bear activity can occur in any area, and safety is not guaranteed.

”Bear activity is especially high during May-August. Visitors may experience a higher likelihood of bear encounters this time of year," the park says on its black bears information page.

Aggressive bears have been a concern in the park since April, with the animals chasing people and even biting them.