Crowds cause of some mountaineer deaths

Experienced climbers and guides called for alpinists without adequate training to think twice about taking on the world's highest peak, especially during a crowded climbing season.

As of Tuesday, the death toll of climbers attempting to reach the summit of Qomolangma - known as Mount Everest in the West - reached 11 during this climbing season. Nine died on the Nepali side and two on the north face of the mountain in China's Tibet autonomous region, according to media reports.

China's Qomolangma climbing season runs from April 10 to this weekend, weather permitting. At least four deaths have been blamed on crowding during the climbs, Agence France-Presse reported.