Rescuers on Monday recovered the dead bodies of eight workers who were swept away by water from a reservoir while building a hydropower dam in northwestern Vietnam two days earlier, Tuoi Tre newspaper reported.

At around 8 a.m. last Saturday, 11 workers were installing turbines for the Suoi Sap 1 Hydropower Plant in Bac Yen District, Son La Province, when water from a reservoir flooded the tunnel in which the workers were standing.

Three workers managed to swim out of the tunnel. Eight others drowned.

As of 10 a.m. on Sunday, rescuers had recovered the bodies of five workers. The remaining bodies were found on Monday morning.

Local authorities said a valve used to close the reservoir failed due to a technical error, which led to the accident.