One person was killed on Friday and several others were wounded when a bomb exploded inside a passenger bus in the southern Philippines, police said, according to DPA. Superintendent Robert Kiunisala said the YBL bus was waiting for passengers outside a terminal in Koronadal City, 1,005 kilometres south of Manila, when the improvised device exploded. Kiunisala said the explosion also damaged a portion of an adjacent appliance store. Investigators said the attack might be the handiwork of extortionists, who have threatened to bomb YBL buses if its owners would not pay protection money. Last month, an explosion also occurred on a YBL bus parked inside a public terminal terminal in Koronadal. One person was wounded in the attack.