DERA ISMAIL KHAN: A head constable was shot dead by unidentified members of a terrorist organisation near the Nawab Adda area of Dera Ismail Khan on Saturday. The terrorists were riding a motorbike and targeted head constable Tahir Khan who was performing census duty in DI Khan. According to sources, Tahir was on his way back home after duty when two motorcyclists shot him dead. Soon after the incident, law enforcers reached the spot and secured the entire area. The police launched a search operation afterwards, which was underway until the filing of this report.