What to know

• There are grave fears for hundreds of people missing, including dozens of Australians, after an avalanche triggered flash flooding at the Nepal-Tibet border.S1
• A total of 403 people unaccounted for, says a Nepal Tourism Board officialS2
• Scientists are trying to figure out what caused such a destructive flood, and dozens of foreign tourists, including nearly 50 Americans, are among those who are unaccounted for.S3
• Alpine Eco Trek, which offers guided tours and expeditions in Nepal, told the Press Association that two Irish nationals were among those missing from its tour groups.S4