At least 11 deaths have been attributed to electrocution, as rising waters become electrified in low-lying urban areas, according to the Edhi Foundation, the city's main emergency aid agency.
Karachi is the latest major South Asian city to be hit by heavy monsoon rains
amid a widening flood-related crisis engulfing much of the region. More than 1,200 have died and upwards of 41 million people have been affected in neighboring India, Nepal and Bangladesh, according to estimates provided by the International Federation of Red Cross and Red Crescent Societies (IFRC).
Figures released by the city's Meteorological Department show Karachi normally receives an average of 19.9mm of rain in September. On Wednesday, northern parts of the city received 97mm, equivalent to five times that amount.
Most of the flooding in Karachi has occurred in the city's predominately industrial northern and western districts.
Shahrah-e-Faisal, one of the city's main avenues has been partially submerged and other nearby roads have become inaccessible.
The flooding comes as many in the city are preparing to celebrate Eid al-Adha, one of the holiest dates on the Muslim calendar. The holiday is typically one of Karachi's busiest periods, as families come together to mark the date.
Though the city's coastal facing southern areas have escaped much of the immediate damage, the flooding has knocked out power supplies, leading to periodic electrical blackouts throughout the entire city of 14 million.
With main roads submerged and business affected, many of the city's markets have been forced to shut down, while the private school association of Karachi has called on all schools to remain shut until the flood waters recede.
A statement from the country's Prime Minister Shahid Khaqan Abbasi said "the government would provide all possible assistance to the provincial government." The Pakistan army has since been mobilized to help assist in the flood relief and drainage efforts.