The South Korean embassy in Nepal says a South Korean mountaineer went missing Sunday while descending Mount Everest with an alpine club of his fellow high school graduates.

The team’s captain Park Gye-hoon told the embassy that 24-year-old Son Won-bin successfully scaled the mountain on Saturday but ran into trouble sometime between Saturday night and early Sunday morning as he descended with another climber.

The embassy says it will look into the incident and discuss measures with the club members.

A dozen graduates of Chungnam High School in Daejon led by Park formed the club to climb Everest in celebration of their school's 50th anniversary. They arrived in Nepal in late March and were scheduled to return home later this month.