4 Die in 4 Days Climbing Mount Everest

— -- Four people have died within four days on Mount Everest, an official at Nepal’s tourism department told ABC News today.

Climbers from Australia, India and the Netherlands have died on the world’s tallest peak since Thursday. A local Sherpa guide was also among those killed, according to CNN. This could not be independently confirmed by ABC News.

Meanwhile, two Indian climbers, Paresh Nath and Goutam Ghosh, have been missing on the mountain since Saturday. They were last seen near the legendary Everest summit, Wangchu Sherpa of the Trekking Camp Nepal agency in Kathmandu told The Associated Press.

The four deaths were the first reported this year on Everest as the busy trekking season nears its end. Two climbers died from altitude sickness, one fell to his death, and one is suspected of dying from a heart attack, CNN reported. The causes of deaths could not be independently confirmed by ABC News.

Rescue teams said there have been recurring calls of climbers suffering from altitude sickness, frostbite, falls and injuries.

"The most common cause for death on Everest is the altitude. There’s not enough oxygen there," said Dan Stretch, a senior specialist in the operations department at Global Rescue, which has evacuated some 30 people since the 2016 climbing season began last month. "The weather can change very quickly. It can be fine one minute and then force winds and heavy snow the next minute."

The 29,035-foot-high mountain was practically empty the two previous years, after fatal avalanches that canceled expeditions. More than 4,000 climbers have reached the treacherous peak since 1953, when Everest was first scaled by New Zealand explorer Edmund Hillary and Sherpa Tenzing Norgay.

Foreigners from around the world are drawn to Nepal’s UNESCO World Heritage sites, ancient temples and, of course, Mount Everest.

The tourism industry, which brings in more than $3 million from Everest climbing fees alone, is Nepal’s chief source of foreign income and contributed almost 9 percent of its GDP in 2014, according to a report by the World Travel and Tourism Council. But the impoverished Himalayan country saw its tourist arrivals drop after deadly twin earthquakes and quake-triggered avalanches last year.

ABC News' Ishwar Rauniyar in Kathmandu contributed reporting.