Gaza, June 19 (IANS) Five Islamic Hamas militants have been killed in a tunnel cave-in close to the border between eastern Gaza city and Israel, a security official in Gaza confirmed Thursday. The Five killed, who were on a military mission in one of the tunnels early Thursday morning, belong to the Hamas movement's armed wing Al-Qassam Brigades, the official told Xinhua on condition of a**nymity. Local media said that the Five Hamas militants were killed in an explosion in the tunnel near Tufah neighborhood in eastern Gaza city.