A sudden collapse high in the Himalayas unleashed a devastating wall of water, ice, rock and debris across Nepal and Tibet — leaving communities cut off and rescue efforts racing against time.

But the immediate destruction may only be part of the story. With unstable lakes now raising fears of another round of flooding, authorities are confronting a disaster that could continue to unfold even as the search for survivors goes on. So what triggered the deadly flash flood and how are the rescue operations going on the ground? 

On The Big Story, Hongbin Jeong speaks to Aftab Ahmed, South Asia Chief Correspondent from Reuters to find out more.