An avalanche on Mount Everest killed 12 and wounded six others on Friday, government officials told CNN.

Around 50 people, most of whom were Sherpa guides, were 20,000 feet up the world's highest mountain when the avalanche occurred, Tilak Ram Pandey, from Nepal's Tourism Ministry mountaineering department, told CNN. Twelve Sherpa guides were killed and three were seriously wounded when the natural disaster struck near the base camp on the mountain's Khumbu Ice Fall.

Four others are still missing, Madhu Sudan Burlakoti, from the Tourism Ministry, told CNN.

"Rescue teams have gone...to look for the missing," Pandey told CNN.                            

The area the climbers and Sherpas were on is also known as the popcorn field, due to the shape of the ice that resembles popcorn, Ang Tshering Sherpa, president of Nepal's Mountaineering Association, told The New York Times.

Friday's avalanche is the single deadliest tragedy ever to occur on Mount Everest. A storm in 1996 struck a group of eight climbers who were never seen again. That same year was the mountain's deadliest, where a total of 15 people died, CNN reported. The second deadliest year was in 2006 when 12 climbers died.          

Nepal's tourism industry is currently preparing for the spring climbing season. Daring climbers arrive by the hundreds to take advantage of the best time of year to reach the summit, which is said to be between May 15 and 30. Over 300 foreign climbers have been given the OK to ascend the mountain this spring, CNN reported.

The climbers are led by guides from the ethnic group Sherpa. The first people to climb to the top of Mount Everest were New-Zealand-born Edmund Hillary and his Sherpa guide, Tenzing Norgay in 1953, according to The NY Times.

Sherpas usually assist foreign climbers with fixing ropes, and risk their lives by being the first to go up the mountain, The NY Times reported.