An official from Nepal's Department of Tourism told Reuters that Christopher Kulish, 62, reached the 29,035-foot peak via the mountain's Southeast Ridge, but passed away suddenly at the South Col, approximately 3,000 feet below the summit.
The specific cause of death was not immediately known.
Christopher Kulish in front of Mount Everest. (Family photo)
In a statement to Fox 31, Kulish's relatives said they were "heartbroken" by the 62-year-old's death. They told the station he reached the summit in ideal weather conditions Monday morning and saw the sunrise. The family also said Kulish was trying to join the so-called Seven Summits club by climbing the highest peak on each continent. Mount Everest was all that stood between Kulish and the successful completion of his quest.
At least nine people have died in recent weeks while trying to climb Everest on the Nepali side during the abbreviated climbing season, which ends this month. Two other climbers have died attacking the summit from the Tibetan side.
Officials say a backlog of climbers and their Sherpa guides has caused delays in reaching the summit that have exacerbated the dangers of altitude sickness, which is caused by low amounts of oxygen at high elevation and can cause headaches, vomiting, shortness of breath and mental confusion.
Last week, 55-year-old Don Cash, from Utah, died of altitude sickness near the Hillary Step while descending from the summit.
The Associated Press contributed to this report.