The Bakhtar News Agency said the flooding took place on Sunday in northern Parwan province. The agency said that women and children were among the dead and 17 people were reported injured.
At least 100 people remained missing on Monday, the report said, and a search and rescue operation was underway.
The flash floods swept away dozens of homes in the three affected districts in Parwan. The province is ringed by mountainous and more often witnesses floods from heavy rains.
The local weather department said more rains were expected in the coming days in most of Afghanistan’s 34 provinces. Heavy rains and flash floods across the country killed 40 people in July and 19 the month before.