The messaging group was set up by engineers before the wall of water, mud ​and rock crashed down the Trishuli valley in Nepal on August 26. KATHMANDU, Sept 4 (Reuters) - An army of experts in a WhatsApp group is guiding rescue workers scouring a Nepali valley after a huge flash flood more than a week ago as they desperately search for anyone who may be alive inside tunnels of devastated hydropower plants. Key points and original sources are listed below.

• The messaging group was set up by engineers before the wall of water, mud ​and rock crashed down the Trishuli valley in Nepal on August 26. It has since become a valuable tool alongside helicopters and heavy ⁠machinery in the race to find survivors.S1

• KATHMANDU, Sept 4 (Reuters) - An army of experts in a WhatsApp group is guiding rescue workers scouring a Nepali valley after a huge flash flood more than a week ago as they desperately search for anyone who may be alive inside tunnels of devastated hydropower...S2S3

• More than 1,200 people were killed in last week’s deluge caused by a glacier collapse. More than 4,000 people are still missing, including those who might be trapped inside tunnels.S4

• Authorities hope some of the roughly 900 people reported missing at six hydropower plants may have escaped the deluge because they worked in or fled into tunnels.S5