For those stranded by a flood, disaster experts say survival depends on access to oxygen, food and water.

School principal Rajendra Dawadi's quick decision to evacuate his school saved at least 900 students from devastating flash floods in Nepal last week.

Flood warning notices were sent to people's phones early Sunday as rescue crews worked to clear a major highway connecting Kathmandu to one of the areas worst hit by Wednesday's catastrophic floods.

The scale of the disaster in the Himalayas is becoming clearer a day after catastrophic flooding tore through parts of Nepal and Tibet. Scientists believe the disaster was likely triggered by the collapse of a glacier, unleashing a torrent of water, mud and debris that swept away entire communities. Geoff Bennett discussed more with Dan Shugar of the waterSHED Lab at the University of Calgary.

The deadly flash flood in Nepal on Wednesday was likely caused by a huge chunk of a glacier that broke off and temporarily dammed a river, according to preliminary investigations by scientists.