GRAND CANYON NATIONAL PARK, Ariz. (AP) — Authorities are searching for a Maryland man who is reported missing at Grand Canyon National Park.

Park officials say they received a report around 9 p.m. Tuesday about an overdue backpacker in the vicinity of the Walhalla Plateau on the canyon’s North Rim.

They say 66-year-old Clifton “Cliff” Beck of Mount Airy had obtained a backcountry permit to spend two nights on the Walhalla Plateau. It is believed that Beck is travelling alone and he was expected to exit the backcountry last Sunday.

Park rangers searched unsuccessfully by aircraft Wednesday for Beck. Thursday’s operations include deployment of nine ground search teams as well as aerial searches by helicopter and fixed-wing aircraft in the Walhalla Plateau area.