At least four people were killed and two injured Wednesday when a roadside bomb exploded in Pakistan's remote tribal area near the Afghan border, officials said. The incident occurred in Gathgay village of Mamond region of Bajaur, one of seven districts where militants are thought to be active. The bomb was detonated by remote control when a group of local residents was passing, Mustaqim Khan of the district administrator's office told DPA by telephone. "So far four people have been confirmed dead and two injured," Khan said. "The identity of those killed is not known." No one had yet claimed responsibility, he said.