An avalanche crashed down the slopes along a particularly hazardous route on Mount Everest early Friday morning, killing at least 12 Nepalese guides and leaving three others missing, officials said, in what is now believed  to be the single deadliest disaster to hit the world’s highest peak.

The Sherpa guides who died had gone early in the morning to fix ropes for climbers when the avalanche hit just below “Camp 2” at about 6:30 a.m., Nepal Tourism Ministry official Krishna Lamsal told The Associated Press. Rescue workers pulled out 12 bodies from under mounds of snow and ice and were still searching for the missing three.

(See photos: The dangerous road to Mount Everest)

Two Sherpas were taken by helicopter to hospitals in Nepal’s capital, Kathmandu.

Tents are pitched on Camp 2 on May 16, 2013 as climbers rest on their way to summit the 29,035-foot Mount Everest. (Pasang Geljen Sherpa/AP)

The area is known as one of the most dangerous, with the glacier moving so rapidly that it opens up crevasses with little or no warning. Towers of ice can collapse suddenly in chunks. It’s nicknamed the “popcorn field” because, from a distance, it resembles a giant bowl of popcorn filled with jagged blocks of ice that have broken off the mountain.

Alan Arnette, a climber, posted on his blog an account from witness Gavin Turner:

I was climbing through the icefall this morning at about 6am when a very large avalanche struck a couple of hundred meters above us. I was with my incredible Sherpa, Phu Tsering. We watched the enormous avalanche cloud approach us and we were both covered in snow dust. After some initial concern, we knew we were safe and essentially out of harms way. Phu Tsering chanted some Buddhist prayers and made an offering to the mountain. The avalanche cloud covered us, but fortunately we were a couple of hundred meters under the impact zone.

There were many climbers and Sherpas above us, higher in the icefall, and an unknown number of them (reportedly all Sherpas) have been killed and injured. The rescue is underway and many Sherpas and westerners were rushing up the mountain to assist in the rescue as I was descending.

I am extremely grateful to be back at base camp and feel deeply saddened and shocked at the loss of life today.

The AP reported hundreds of climbers and guides had gathered at the base camp, preparing for their final attempt to scale the 29,035-foot peak next month when weather conditions are more favorable. They have been setting up camps at higher altitudes with guides fixing ropes on the slopes before the final climb in May.

Nepal had announced steps earlier this year to better manage the flow of climbers, minimize congestion and speed up rescue operations. The preparations included the dispatch of officials and security personnel to the base camp at 17,380 feet, where they would stay throughout the spring climbing season that ends in May, the AP stated.

Agence France-Presse said this avalanche is among the worst to strike the mountain. Eight climbers died in one day in 1996 because of a snow storm in areas near the summit. It was immortalized in the book “Into Thin Air” by journalist Jon Krakauer. Also, six Nepalese guides were killed in an avalanche in 1970.

More than 4,000 climbers have scaled the summit since Sir Edmund Hillary and Tenzing Norgay did it in 1953.

Hundreds have died attempting to reach the peak.

(See photos: The dangerous road to Mount Everest)