DERA MURAD JAMALI: A traffic police constable was killed and three passers-by injured when a bomb planted in a bicycle went off in Dera Allah Yar, Jaffarabad District Police Officer (DPO) Suhail Ahmed Sheikh said on Thursday. Some unknown suspects had parked an explosive-laden bicycle at Sohbatpur Road. The resultant blast killed traffic police constable Muhammad Ishaq on the spot while three other citizens Ali Sher, Nadir Ali and Muhammad Nawaz were seriously injured. Police have registered a case.