New Delhi, July 22 -- KABUL - Rescue teams were picking through collapsed buildings and blocked roads in Afghanistan's Nuristan province Tuesday after flash floods killed at least 23 people and left more than 100 missing, with Afghan authorities warning that ten of the country's 34 provinces faced the risk of further extreme weather as the regional monsoon intensified across South Asia.

The floods struck on July 20 and continued into the following day, sweeping through villages in the mountainous northeastern province and destroying homes, shops and road infrastructure. The pace of the destruction outstripped the capacity of local rescue teams, who were hampered by damaged access routes as additional rainfall threatened to complicate ope...