Local news reported the boy had been walking past a cafe and didn't see the open drain beneath the murky knee-deep water.
The video shows the commotion, as passersby stare at the vortex of flood water rushing down the drain; a witness who watched it happen insists there is a child submerged, even though there is no sign of him.
A group of quick-thinking men grab bamboo poles and jam them into the drain, in the hope the boy might be able to somehow grab on.
Members of the group then desperately plunge their arms into the raging water; it looks like a completely hopeless situation — until they pull the boy up and onto the sidewalk.
There were reports online that the child had died; however according to a local news report, he was semi-conscious when pulled from the water and rushed to hospital, where he made a full recovery after medical treatment.
Karachi sees a hot desert climate all year round, aside from the July-August monsoon season when virtually all of its rain falls, an incredible strain on the city's already beleaguered drainage system which overflows between 2-7 times per month, according to a 2017 report.
In Orangi specifically, residents self-organized to create their own sewage system, built by volunteers.
Several children have drowned or even been electrocuted by downed power lines in flood waters in the region over the years; a number of videos shot in Orangi Town last week show just how bad the flooding situation is: