Pakistan ordered businesses, schools and public offices in Karachi to shut on Wednesday after torrential monsoon rain left at least 10 people dead in the densely populated port city, with more heavy downpours predicted.

At least 21 people have died in monsoon rain-related incidents in Pakistan, authorities said, pushing the nationwide death toll over the last week above 400 as floods and landslides continue to devastate large parts of the country.

Rescuers were racing against time to find survivors after flash floods killed at least 337 people in Pakistan 's Khyber Pakhtunkhwa province. The northwestern province was struck by cloudbursts and torrential monsoon downpours on Friday, triggering flash floods and landslides in the mountainous Buner district.