PT. REYES NATIONAL SEASHORE, Calif. » One person is dead and another being treated for life-threatening injuries after a bluff collapsed at a popular Northern California hiking trail.

San Francisco television station KPIX reports that the two visitors were standing on the Arch Rock lookout point at Point Reyes National Seashore just before 6 p.m. on Saturday when the bluff gave way. The pair fell about 70 feet and were covered with rocks and debris.

The National Park Service had posted signs at the site two days earlier warning hikers that a fissure along the top of Arch Rock may have weakened the cliff and that walking along the edge was dangerous.

One of the hikers was pronounced dead at the scene. The other was airlifted to a hospital. They have not been identified.