A teacher and 13 children suffered minor injuries after the ceiling of an indoor gym at an elementary school in Yeosu, South Jeolla Province collapsed around noon Friday. 

According to firefighters and rescue authorities, a dozen of the injured including the teacher were transported to hospital while the two other students went to hospital on their own for treatment. 

Authorities believe a structure inside a section of the ceiling above the stage in the gym lost integrity and collapsed, with debris falling on the teacher and several third graders who were rehearsing on stage for a school performance. 

Authorities plan to determine the exact cause of the collapse through a further inspection.