Disaster then hardened around the remaining climbers like a quick freeze. Cooperation largely ceased and climbers abandoned each other, van Rooijen said.
"They were thinking of my gas, my rope, whatever," he said. "Actually, everybody was fighting for himself and I still do not understand why everybody was leaving each other."
Some wandered off on their own in near suicidal acts of desperation.
"People were running down but didn't know where to go, so a lot of people were lost on the mountain on the wrong side, wrong route," van Rooijen said.
He said at one point he spent hours searching for a camp in The Bottleneck, lost because other climbers who had promised to plant flags to mark the way failed to do so.
"Some climbers did not take their responsibility and then accidents like this happen very easy," van Rooijen said.
He went without food and water for several days and had to sleep without a sleeping bag. Swedish survivor Fredrik Strang told CNN that in the morning, he would find fellow climbers frozen to death.
Van Rooijen said the descent was made even more perilous by either thick clouds that made it difficult to see where he was going or the glare of the sun off the snow and ice that was so intense it threatened to blind him.
At one point, the Dutchman stumbled across a trio of Korean climbers who appeared to be in an almost hopeless situation.
One was dangling upside down by a rope. A second Korean held desperately to one end of the rope to keep his colleague from plummeting into an abyss. The third Korean sat dazed in the snow.
"They were trying to survive," van Rooijen said Monday. "But I had also to survive because I was getting snow blind."
He said the Koreans declined an offer of help, believing rescue was on its way. Three Koreans are listed among the dead and missing, although it's not clear if they were the ones that van Rooijen saw.
Van Rooijen worked his way far enough down the mountain to be plucked to safety by a helicopter Monday, along with a fellow Dutchman, after suffering frostbite that may cost him several toes.
Among the dead were three Koreans; two Nepalis; two Pakistani high-altitude porters; French, Serbian, and Norwegian climbers; and an Irishman.
The French climber presumed dead, Hugues d'Aubarede, relayed an account of the climb that was posted on a blog. His last message, from the foot of the Bottleneck, was: "I would love it if everyone could contemplate this ocean of mountains and glaciers. They put me through the wringer, but it's so beautiful. The night will be long but beautiful."
The Associated Press and Reuters contributed to this report