An 18-year-old was killed Wednesday when his tractor overturned in Beit Ummar near Hebron, medics saidMohammad Jaber al-Slaibi was dead on arrival at the Al-Ahli Hospital, medics told Ma\'an.He died immediately when his tractor overturned and his body was taken to hospital by a Red Crescent ambulance, said Mohammad Awad, spokesman of Beit Ummar popular committee.Police are investigating the incid