A rock slide that unleashed boulders "the size of trucks" killed a climber and injured two other hikers as they descended Mount McKinley, authorities said.

It was one of two deadly rock slides in the United States over the weekend.

On Saturday, a rock slide on a popular trial on Mount Katahdin (search) in Maine killed a hiker who became trapped under a boulder. The victim was identified as Roger Cooper, 52, of Bangor, Maine.

In Alaska, four climbers were attached by rope at 13,000 feet when giant boulders began raining down on them Sunday. Two men suffered non-life-threatening injuries, while a fourth, a guide, was not injured.

Clint West, 47, died of multiple injuries shortly after the rock slide. West was an experienced climber who, though an American, lived in Oxfordshire, England, with his wife and three daughters, said Colby Coombs, co-director of the Alaska Mountaineering School (search), which led the expedition.

National Park Service officials said the rock slide had falling boulders from 2 feet to 10 feet in diameter. National Park Service (search) officials called it highly unusual for a rock slide of that size to occur on that part of the mountain. They were not sure what caused it.

Mount McKinley (search) is the highest peak in North America at 20,320 feet.