TODAY | May 23, 2012
>> a serious story. the harrowing new details about the deaths of four climbers who perished over the weekend trying to reach the summit of mt. everest . this morning we're hearing from a colorado man who was there. here's nbc's miguel almaguer.
>> reporter: piercing 29,000 feet into nepal 's sky, mt. everest is the world's tallest peak. but the mountain is also one of the deadliest. this weekend climbing four lives while three other climbers are said to be missing and feared dead.
>> we came across two more bodies that were also not moving at all.
>> reporter: john, a mountaineer from colorado was on everest sunday. as he descended the mountain he came across some of the victims. a 16-year-old german doctor, a graduate student from nepal , and a south korean climber who he tried to help.
>> his hat was off, his gloves were off. he was kind of looking at me, kind of zombie-like. or anybody that would pass would reach out and try to hand you. the gentleman's hand was frozen solid.
>> reporter: the climbers had been waiting at a campsite like this one in the so-called death zone because of the mountain's icy slopes, and low oxygen level. when the weather finally cleared, an estimated 150 climbers rushed to reach the summit. mountaineers describe the scene as a traffic jam . but soon, a windstorm blew in, there was nowhere for climbers to go. supplies started running out.
>> when there's a bottleneck on everest , you have a long line of climbers that really can't pass one another. they're stuck. they're using up their oxygen, and as a result, they get cold, and potentially make bad decisions.
>> reporter: it's believed the victims died from hypothermia and brain swelling triggered by the lack of oxygen and high altitude . the bodies are so difficult to reach, they may never be removed from the mountain. the graduate student from nepal tracked the early stages of her climb on facebook. but words of encouragement turned to condolences as news spread of the tragedy. on everest , the weekend will be remembered as one of the deadliest in history. a mountain crowded with climbers, a trip not everyone would survive. for "today," miguel almaguer, nbc news, los angeles .