Massive landslides and flash floods on the Nepal-Tibet border have caused widespread damage and left hundreds dead or missing.
Search and rescue operations have been ongoing since Wednesday's disaster. Chinese state media has said there are significant casualties, while Nepalese officials describe "huge scale loss".
But rescuers are on edge because of the risk of further flooding. A lake of rising water which has formed at a site along the border briefly overflowed early on Friday, prompting Chinese authorities to pause rescue efforts, according to state media.
Here is what we know so far.
Initial reports of an earthquake on the Nepal-Tibet border led many to believe that a tremor had caused a landslide, which in turn caused the devastating flood.
However, the US Geological Survey has clarified that the disaster was caused by a "glacial collapse", which is when a glacier or part of a glacier disintegrates.
The impact of the collapsed glacier hitting the bottom of a valley was so powerful that it registered a magnitude of 5.2, according to USGS data and scientists who have analysed the event.
Debris flow from the collapse "caused subsequent catastrophic impacts downstream" the USGS said.
Climate change is known to be driving faster glacier melt in the Hindu Kush Himalaya region. Scientists are trying to piece together the exact order of events as rescue efforts continue.
Geologist Daniel Shugar – one of the first experts to suggest Wednesday's flash flooding event could have been caused by glacial activity – says glacial thinning inducted by global warming can increase the risk of landslides.
But it is still too early to definitively link the event to climate change, Shugar, who is based at the University of Calgary in Canada, tells the BBC.
Simon Cook, a geoscientist at the University of Dundee, says however, that climate change "could have an impact". Cook added that his team believed they had identified where the collapse had occured. He told the BBC that the lower part of a glacier in Nepal near the Langtang Lirung peak - approximately 15km (9 miles) west of the site of the floods - had collapsed.
He estimated that the glacier collapsed in a north-westerly direction and then travelled westwards downstream.
He told the BBC "permafrost is partially holding some mountainsides together, this permafrost is warming and thawing and degrading so you are going to get more landslides".
Mike Searle, professor of Earth sciences at Oxford University, said the glacier could have collapsed "hours or days" before the flooding hit Nepal and Tibet.
He told the BBC: "I think the sheer wave of debris suggests there was a landslide first, the water built up, (which) dammed the river, and then it burst in one huge great flood."
One possibility is that water from rainfall or melting ice may have destabilised the ground or ice, triggering a chain reaction.
Scientists will be looking at satellite images of exactly where the landslide occurred, whether any glacial lakes suddenly drained, and where the river might have become blocked, as well as data on recent rainfall.
A deluge of material careered towards northern Nepalese towns, including areas popular with mountaineering tourists and pilgrims. The border is around 40 miles (64.4km) north of Nepal's capital city Kathmandu.
Footage showed a wall of mud and rock sweeping away buildings, roads and vehicles, as people fled the fast-moving wave of material in the Nuwakot region.
In one video, a towering wall of water and mud was seen rushing down a gorge along the Trishuli River and enveloping the Rasuvagadhi Border check point, a multi-storey building.
Severe flooding has been reported along the Bhote Koshi, Trishuli and Narayani rivers.
Deaths have also been reported in villages on the Tibetan side of the border.
The International Centre for Integrated Mountain Development (ICIDMOD) has warned secondary flooding could occur in the coming days as a result of the debris that washed into the river systems.
The ICIDMOD said they are assessing whether the Trishuli River has been temporarily blocked in narrow sections. If it has been blocked, it is at risk of forming a landslide dam and a second flood.
Secondary flood warnings have put people "very much on edge", David Fisher, head of the Red Cross' delegation in Nepal, tells the BBC.
The number of people killed or missing is still becoming clear.
Nepali police said at least 475 people had died as of Friday morning local time, with hundreds still missing. Among those killed, 64 were found in downstream areas in the Chitwan district while another 26 were found in Nawalparasi East.
Nepal's National Disaster Risk Reduction and Management Authority said 910 people were still missing as of Thursday evening. This included 517 foreign citizens, 44 members of the Nepali army and 28 police officers.
The Nepal Tourism Board meanwhile said 644 tourists were still missing, 33 of which were UK nationals, including a 13-year-old girl and 14-year-old boy. It is unclear if any of them are included in the latest death toll.
Nepal's Prime Minister Balendra Shah said "the entire nation has been left shocked and deeply distressed" and that officials would coordinate with China on the response.
China's President Xi Jinping urged an "all-out" search and promised stronger monitoring and early warning systems to prevent secondary impacts.
In neighbouring India, Prime Minister Narendra Modi said his government was "prepared to provide Nepal with all possible types of humanitarian assistance".
UN Secretary General António Guterres says he is "saddened by the severe flooding", adding that UN teams and partners are mobilising supplies and personnel in Nepal to support the government-led response.
The US has promised $500,000 (£367,982) in aid which will be used to cover emergency shelter, water, sanitation and other relief items for communities affected by the floods.
Prime Minister Andy Burnham said the UK has offered £5m to help the Nepalese government and will do "everything we can" to support British nationals in Nepal.
Tourists from all over the world come to Nepal for its mountains and sacred sites. Official figures have suggested at least 291 foreigners are among the missing, including:
India - the Nepal Tourism board says 288 nationals from neighbouring India are missing
China - The Chinese foreign ministry says nearly 100 Chinese nationals are missing in Nepal
US - the latest update from Nepal's tourist board is that 65 US tourists are known to be among the missing
Ukraine - Ukraine's foreign ministry says 53 Ukrainian nationals are missing
Malaysia - 51 Malaysians travelling with Fishtail Tours and Travels are missing in the floods, officials say
Australia - Australia's foreign minister says 39 Australians are among the missing and there's an "unfortunate possibility" the number will rise
UK - Nepal's police say 33 British nationals are missing
Canada - a tourism board spokesman in Nepal says 24 Canadians are reported missing
Smaller numbers of travellers from South Korea, South Africa, Portugal, the Netherlands and New Zealand are also among the missing.
