160 dead, hundreds missing: What we know about the Nepal-Tibet disaster

Catastrophic flooding and landslides on the Nepal-Tibet border unleashed waves of water and debris that have killed 160 people and left hundreds more missing.

Nepal's disaster agency said that 823 people remained out of contact on Thursday, more than 24 hours after a deadly flood tore through the border region with Tibet.

The 823 include at least 579 tourists, both Nepali and foreigners, it said in an update. At least 165 people are confirmed killed in both Nepal and China, where a further 558 people are reported missing.

Catastrophic flooding and landslides on the Nepal-Tibet border unleashed waves of water and debris that have killed at least 160 people and left hundreds more missing.

The exact sequence of events is still unclear, but on Wednesday morning, torrents of water and debris crashed downstream on both sides of the border.

Surveillance video from the Chinese side showed a wall of mud and water crashing over a building as terrified people ran away.

In Nepal, a surge of water hit villages and towns on the path of two rivers -- Bhote Koshi and Trishuli.

The disaster was intially described as a flood on the Nepalese side, and a mudslide by Chinese authorities.

At least 165 people have been reported dead, 162 in Nepal and three in Tibet.

Chinese authorities have said the disaster caused "major casualties" and reported another 558 missing -- 260 of whom are foreigners.

On the Nepalese side, authorities said Thursday that 468 tourists, 393 of them foreigners, were unaccounted for.

The missing include Indians and others from Ukraine, Malaysia, the United Kingdom, South Africa and elsewhere.

Promises of aid and assistance came in soon after reports of the scale of the disaster.

The United States has pledged $500,000 in emergency assistance, and the International Federation of the Red Cross and Red Crescent Societies released $1.4 million.