dozens of people clambering around debris of dharahara tower in kathmandu to take selfies in front of wreckage .
taking pictures amongst rubble of historic nine-storey structure , which has been reduced to pile of red brick dust .
but one rescuer said those taking photographs of themselves and friends were not ` understanding the tragedy '
not clear how many people were killed in tower in quake-hit city , but it was said to have been filled with tourists .