Transcript for Mt. Everest Tragedy: At Least 12 Dead
Diane is off with her family for the holiday. We begin with an avalanche on Mt. Everest. Looking like a war zone to many. Happened just above base camp. This is what it looks like on the ground. Each tiny dot, a person. And the sherpas helping others conquer Everest. Standing by, one of your own. First, what we're learning about the missing and the sur vi vors. David Kerley leading off. Reporter: The highest point on the planet, it's beautiful but forbidding and unforgiving. Gavin turner heard the massive avalanche. A wall of ice and snow. He thought he would die. It was coming down, and for a few seconds, I thought, this was going to take me out. Just after 6:30 in the morning, a massive cleaving of ice and snow came down. A dozen sherpas missing, buried under the ice. Helicopters carried the injured down the mountain. They were probably close together near the center of the avalanche. Reporter: Since the first summit in 1953, sherpas have been the backbone of climbing to the top of the world. Today, setting ropes on the roadway up the mountain. Mountain guide Robert link has been on five expeditions and summited. Give me a sense of what this is like. It's a black day around the world. Reporter: Eight lives were lost in a storm. Neil beadleman got several safely down the mountain. Things can go wrong in a big way in a hurry. Reporter: At least 250 have been killed on the mountain. David? Thank you. I want to bring in Diana Williams. Who just left base camp. And I know you just made the climb. This time, not with your son. But you told me you witnessed avalanches yourself. At least four in a two-hour period. This was an ice avalanche, extremely dangerous. And happening not far from base camp, which is where you were. Folks coming down from camp one above to help, and people coming up from base camp to help as well. And among the missing, the people that guide and protect groups going up the mountain. They do so much work. Cooking meals, climbing the mount mountain. Everyone is absolutely heartbroken. I am, too. It's extremely sad. Thank you, and safe trip home. Back here to breaking news about terror in the heartland,
This transcript has been automatically generated and may not be 100% accurate.