BANNU: Two persons, including a passerby, were killed and one injured when gunmen opened fire on a petty dispute in the district, police officials said.They said that employees of the District Headquarters Hospital exchanged harsh words over some issue. They said that the accused Khalid, Ijaz, Danish and Pervez opened fire, killing a hospital employee Waseem and a passerby Latifullah on the spot. They said another person Faizan sustained injuries in the incident. The police lodged a case and started an investigation.