A 60-year-old woman from Windsor, N.H., suffered second- and third-degree burns to her lower leg while walking off-trail in a thermal area at Yellowstone National Park.

She broke through a thin crust over scalding water near the Mallard Lake Trailhead on Monday. Her husband and dog were unharmed.

The woman was treated at a park clinic and airlifted to a regional medical center; her condition is unclear.

Park officials emphasize that leaving designated trails is prohibited due to the fragile ground and scalding water beneath the surface, NPR has reported.

This is the first thermal-related injury at Yellowstone this year, where such incidents are common.

Written by B.C. Begley