A 5-year-old boy in Pennsylvania was shot and killed Monday night by his 6-year-old sibling after they were left unsupervised in a room with an unsecured firearm, police said. The Allegheny County Police Department responded to a Penn Hills home at around 5:30 p.m. and found the boy with a single gunshot wound, according to a statement from the department. He was rushed to Children’s Hospital of Pittsburgh where he was pronounced dead.The statement from police said three children had been left alone in a bedroom with an unsecured gun. “Detectives discovered evidence suggesting that a 6-year-old sibling accidentally shot the victim while handling an unsecured firearm present inside the residence,” the statement said. The firearm is legally owned by a parent, who is cooperating with investigators, police said. The child was identified by the Allegheny County Medical Examiner as Connor Wolfe.He attended kindergarten at Penn Hills School District, which said Tuesday that it would have counselors available to students and staff. “We ask all members of our PH community to remember Connor and his family in your thoughts and prayers,” the district said in a statement.Elisha Fieldstadt is a breaking news reporter for NBC News.