Karachi- Unknown men gunned down a head constable of police deployed on court duty today on Karachi's Mohammad Ali Jinnah Road. The officer was shot near Tibet Centre on M A Jinnah Road while he was travelling towards the city's Civic Centre. The officer died on the spot and his body was shifted to Civil Hospital. Meanwhile, another person was killed in Liaquatabad. The deceased was a resident of North Nazimabad.