A volunteer Southport reserve police officer was arrested Thursday on suspicion of holding an unloaded gun to his wife's head and pulling the trigger, police said.Timothy Trefry, 44, was arrested at his Greenwood-area home after his wife called her mother and asked her to summon police Thursday night, authorities said.Police said they believe Trefry, who was off duty, and his wife had been arguing at the home."He allegedly pointed a firearm at her (and), in the process, pulled the trigger on the firearm," said Col. Doug Cox, chief deputy of the Johnson County Sheriff's Department.Children left the home through a window during the argument, police said. No injuries were reported.According to a police report, Trefry's wife told investigators that he previously had threatened to kill her and their children.Trefry, who works as a security guard for Kroger, began volunteering as a reserve officer with Southport police in January. He will no longer volunteer for the department, Southport Police Chief Duane Burgess said Friday."His services are no longer needed here in Southport," Burgess said.Trefry was arrested on a preliminary charge of intimidation with a firearm.