54-year-old Mahendra Singh Thakur, who was a peon in the district co-operative bank here, had a dispute over a minor issue with the security guard, identified as Tejnath Mishra, Lordganj police station In-charge Sushil Chouhan said.
The accused got infuriated and warned the victim to get out of the bank premises, failing which he would shoot him, the policeman said.
When Thakur refused to comply, the accused fired at him from his double-barrel gun, he said, adding that the victim was rushed to a hospital, where he was declared dead.
The incident created panic in the area.