ZAMBOANGA CITY: At least four people were injured after a bomb went off inside a Bachelor Bus unit after making a short stopover in Barangay Hayanggabon, Claver town, Surigao del Norte province on Wednesday. Although no one was reported dead, the explosion was reported to be strong enough to tear the left side of the deluxe air-conditioned bus. The bus was heading for Tandag City from Surigao City. Members of the 30th Infantry Battalion were dispatched to help policemen secure the area as investigation continues. Army Major Ezra Balagtey, spokesman for the Eastern Mindanao Command, said police investigators are determining the type of bomb used in the attack. No individual claimed responsibility for the bombing, but it occurred just as security forces tightened its watch on possible terror attacks following the killing by police commandos of Malaysian bomber Zulkifli bin Hir, alias Marwan on January 25 in Maguindanao’s Mamasapano town. It was not immediately known if the bombing was connected to the killing of Zulkifli.