At least three political activists were killed in poll violence in Pakistan's Khyber-Pakhtunkhwa province, media reported on Wednesday.According to police, supporters of a Pakistan Muslim League-Nawaz candidate, who had lost the election, opened fire at Pakistan Tehreek-i-Insaf workers, killing three of them and injuring two others, Dawn reported.With these killings, the toll in poll-related violence in the province has risen to 21.On Monday, a councillor-elect of Chammad village council was killed by rivals when he on his way back to home.Khan Mohammad was elected chairman of the council in the election last week.