The government is asking North Korea for an explanation about a flash flood on the Imjin River that has presumably killed six South Koreans.

Unification Ministry spokesman Chun Hae-sung said the government sent a message to the communist state on Monday expressing regret over the massive damage.

The South Korean government suspects the flood was caused by the North's apparent discharge of an estimated 40 million tons of water from its Hwanggang Dam near the inter-Korean border without prior notification.

Seoul also asked the North to notify the South beforehand of any future plans to release water from any of its dams.

He added that the government will decide whether to propose inter-Korean talks on preventing flood disasters after assessing how the North responds to the latest incident.

Earlier on Sunday, six South Koreans who were camping along the river near the border with the North were swept away when the river’s water level suddenly surged. Three were found dead on Monday. The search goes on for the others.