Rescue teams and military helicopters are searching for hundreds of missing people along the mountainous Nepal-Tibet border after a huge torrent of water and mud swept through communities following a glacier collapse on Wednesday.

More than 390 people were killed, authorities in Nepal and China said, and more than 1,400 were missing, including hundreds of foreign citizens and pilgrims.

Nepal and China both warned of new flooding ⁠risks in the Himalayas because of two lakes that have developed along debris-choked rivers on either side of their border. Nepal’s disaster authority said water levels were rising in a lake formed by debris clogging a flooded site and ‌that it was at risk of bursting its banks. It did not name the specific site. Chinese authorities warned that a newly formed lake at the confluence of the Tsogyal and the Purupqiangzangbu rivers was overflowing and might burst.

More than 500 foreign citizens were among 826 people missing in Nepal, police and tourism ⁠officials said. Among those unaccounted for were 177 from India, 90 from the US, 34 from Australia, 33 from Britain and 25 from Canada.

Chinese state media said at least 558 were missing on the Tibet side of the border, of whom at least 260 were foreign nationals.