According to police officials, some unidentified bike riders arrived at a private school located in Gulshan-e-Iqbal Block 7 area and threw a grenade near its main gate.
They said none was fortunately injured in the early morning attack, adding that the attackers also dropped a threatening letter and fired aerial shots before fleeing the scene.
The bomb attack prompted DG Rangers Major General Bilal Akber and DIG Munir Sheikh to arrive at the scene.
On the other hand, Governor Sindh Dr. Ishrat-ul-Ibad Khan and Sindh Education Minister Nisar Khohro took notice of the incident and sought report from Karachi police chief.
Meanwhile, a body of private education institutions called a meeting following the incident and called upon the government to enhance security of private schools in Karachi in the wake of terrorist threats