Police in Pakistan say a bomb blast targeting voters at a polling station has killed five people and wounded several others in the volatile northwest, AP reported. Police official Imran Khan says the Sunday explosion occurred in Buner, a district near the Swat Valley. The Pakistani army has waged an offensive against militants in Swat that dates back to 2007, but violence has also occurred in nearby regions. The polls were open for a by-election for a National Assembly seat.