KARACHI - At least four people, among them a DSP and a sub-inspector, were killed and over dozen others wounded in twin blasts in Quaidabad area of Karachi on Thursday. Reports say a low intensity blast took place in Garbage Yard located on Rehri Road in Muzafarabad Colony and as a team of law enforcers, the Bomb Disposal Squad and various welfare organisations reached the spot, another explosive device went off, wounding DSP Kamal Mangan, SHO Quaidabad Amanullah Marwat, other policemen and rescuers. The injured were ferried to Jinnah Postgraduate Medical Centre, where four of them, including DSP Mangan, succumbed to their injuries.Dr Seemi Jamali, head JPMC emergency ward, said DSP Mangan and a cop, namely Akbar, were pronounced as brought dead. The doctor said that at least fifteen people wounded in the blast mostly sustained pellet wounds in the lower torso of the body. She added that two of the injured were fatally hurt. DIG East Aleem Jafri, while interacting with the media at the JPMC, said that terrorists had exploded a low intensity blast in Garbage Yard with the aim to invite the police force and then target them. He also said that four of the wounded people were shifted to PNS Shifa Hospital. Officials of the Bomb Disposal Squad said the first bomb was concealed in a box and the second bomb was placed in cemented block. The experts said that two-kilogram explosive material and pellets were used in the second bomb. Witnesses said that two police mobiles and two ambulances were smashed and windowpanes of nearby buildings shattered in the two bombings.