They returned to the lodge the next day, only to start showing the same symptoms and be again transferred to the hospital. One of the two died Wednesday night and the other early Thursday.

The cause of their deaths was not immediately known.

The university said 17 others in the volunteer group, including professors, remain sound and healthy.

It plans to send officials to deal with the aftermath and to figure out what exactly happened. The parents and families of the victims have been notified of the incident, and they are arranging flights for them, the university said.

The 19-member volunteer group left for Cambodia on Sunday to participate in an aid program to help residents there build necessary facilities and equipment. They were originally set to come back next Wednesday, but they now are planning on an early return, officials said. (Yonhap)