KATHMANDU, Nepal (AP) — Three Sherpa climbers were missing Wednesday after they fell into a deep crevasse on a treacherous section of Mount Everest just above the base camp, a Nepalese mountaineering official said. Hundreds of foreign climbers and about the same number of Nepalese guides and helpers are expected to attempt to scale the 8,849-meter (29,032-foot) mountain during the main climbing season that began in March and ends at the end of May. Climbers have begun to settle in at the base camp to acclimatize to the weather and altitude while the Sherpas place ladders and ropes and carry supplies to the upper camps for their clients