KARACHI –A mysterious blast took place at Pathan Colony, Banaras within the jurisdiction of Site police station.Police officials said that the bomb was lying under the intercity bus bearing registration number C-2352 and exploded suddenly. At the time of blast, no one was near the bus, therefore the blast was not harmful while the bus damaged. After getting information, police and other authorities concerned reached the spot to examine the nature of blast.Experts of Bomb Disposal Squad (BDS) collected available evidences to examine the nature of blast. The Bomb Disposal Squad official said that explosive device was carrying 65 grams of explosive materials. Police suspect that extortion mafia could be behind the incident.