Searchers were looking for a missing backcountry traveler near Eagle Peak in Yellowstone's southeastern corner/NPS file

A search-and-rescue mission was underway Sunday in the remote southeastern corner of Yellowstone National Park for a 22-year-old who failed to meet a scheduled boat pickup on Friday.

Austin King, a concessions employee, had set out for a seven-day trip to Eagle Peak and back. While he called friends and family from the mountain's summit on Tuesday, he hasn't been heard from since then. At 11,372 feet, Eagle Peak is the highest point in the national park.

The search-and-rescue operation, involving teams from Yellowstone and Grand Teton national parks and Park County and Teton County in Wyoming, was focused in the vicinity of Eagle Peak, the Eagle Pass Mountain Creek Trail, and the Eagle Creek Trailhead in Shoshone National Forest.

King was described as standing 6 feet tall, weighing 160 pounds, with brown hair and hazel eyes. He was wearing glasses and might have been wearing a black sweatshirt and gray pants, a Sunday evening release from Yellowstone said.

When he talked to friends and family from the mountain's summit, King described rain, sleet, hail, foggy and windy conditions.

On Saturday an aerial search along with ground teams was conducted in the area. Searchers found King's camp and personal effects Saturday evening in the upper Howell Creek area, the park release said.

On Sunday the search involved more than 20 ground searchers, two helicopters, drones, and a search dog team.

Park officials are asking for information from anyone who might have been traveling near Eagle Peak since September 14 and might have encountered King. Information should be provided the Yellowstone Interagency Communications Center at 307-344-2643.