Soon after the incident, Union HRD Minister Smriti Irani inspected the site, which is close to Gole Market.
Fire officials said the 20-feet high wall collapsed around 11 AM.
Although four passers-by were injured, no student was hurt in the mishap, the officials said.
"The injured have been admitted to RML hospital," an official said, adding they included a barber and his customer.
According to an eyewitness, two persons received grievous injuries as they were sitting right behind the wall.
"It suddenly came down on the side of the footpath which is usually lined with barbers and fruit vendors," he said.