The deaths from Tuesday's rain were reported in the eastern city of Lahore, where residential areas flooded. It also exposed flaws in the sewer system, which flooded some of the city's streets.
According to the Meteorological Department, more heavy rains are expected this month, AP reported.
Every year, many cities and towns in Pakistan struggle to cope with the annual monsoon deluge, drawing criticism about poor planning.
Pakistan's monsoon season runs from July through September.
Rains also swell rivers during the monsoon season, causing floods that kill people and damage crops and infrastructure.