Emergency staff worked through the night to pull people from beneath twisted metal and other debris and rush the injured on stretchers to waiting ambulances. Snow, sleet and icy roads hampered rescue operations.
The collapse happened Monday night. About 560 students from Busan University of Foreign Studies had gathered for a two-day freshman orientation at the Manua Ocean Resort in the southeastern city of Gyeongju when a crack appeared in the auditorium ceiling before the collapse.
Recent heavy snow combined with rain likely put too much pressure on the structure, said Kim In-you, a fire rescue squad team leader for the Busan Fire Department.
Ten people died, two people were seriously injured and 103 lightly injured, said Jung Yoon-han, director of the disaster management department at the Ministry of Security and Public Administration.
The students had just finished dinner and were gathering for recreational activities at the time of the collapse, Byun Ki-chan, head of the international exchange department at the university, told reporters Tuesday. Some managed to escape after noticing a crack in the roof but others couldn't leave in time, he said.
Gyeongju is a historic city and popular tourist destination that served as the capital of one of the Korean Peninsula's ancient kingdoms.
Located at an altitude of about 500 meters (1,640 feet), the resort is at the foot of Dongdae Mountain, according to the resort's website. Weather officials said the area has received heavy snow over the last week.