Rescue workers search for the teenagers in the Red River on November 18.
Reports from the Phu Tho Provincial Police Department said that six 8th-grade students of Hien Quan Secondary School went to the Red River to swim at 4 pm on November 18 while on their way home from school.
The three girls and three boys were then trapped in a whirlpool. A boy managed to swim back to shore while five others were swept away.
Rescue forces arrived soon after, and they found the body of a girl at 7 pm that night.
Speaking to the media early on the morning of November 19, Nguyen Manh Hung, Vice chairman of Tam Nong District People's Committee, said that rescue workers searched through the night but had found nothing.
"The search is continuing," the official said.