(CNN) -- A 12-gauge shotgun loaded with bird shot accidentally discharged Saturday when the owner opened its case at a gun show at the North Carolina State Fairgrounds in Raleigh, injuring a retired sheriff's deputy and two other people, police said.

The gun owner, a 36-year-old man from Wilmington, North Carolina, was carrying the weapon through security at the show entrance and was unfastening the case on a table, authorities said. The owner planned to sell the shotgun at the show.

The deputy suffered a slight injury to his hand and was treated and released at a local hospital, said Joel Keith, chief of police of the North Carolina State Fair. A 54-year-old woman from Benson, North Carolina, was being treated a wound to her right torso at a local hospital, and a 50-year-old man from Durham, North Carolina, was treated for an injured left hand, Keith told reporters.