Three students have been reported missing after they were swept away by a wave in a swimming zone off the central Quang Ngai Province.
The three students had gone swimming during the Tet holiday (Lunar New Year) with 11 other 11th-grade students from the province's Tu Nghia II high school.
Rescuers at My Khe beach, where the students came to play and swim, said they were swimming far away from the shore when a strong wave suddenly hit them.
The rescuers saved 11 boys. Three went missing, despite the rescuers' attempts to save them.
The beach management said that converging winds from different directions in the sea have created a whirlpool that is dangerous for swimmers. All services at the beach have been shut down and emergency warning signboards have been put up.