The incident occurred this afternoon in Shivajinagar area of Govandi when two boys were playing near the wall of a school run by Municipal Corporation of Greater Mumbai, which was being re-constructed, an official at Shivajinagar police said.
The wall collapsed just as two others were passing from the area.
The deceased has been identified as Aazam. The injured were admitted to two separate local hospitals and their condition is stated to be out of danger, he said.
A case has been registered in this connection and investigations are underway, police said.