GETTYSBURG, Pa. (AP) - A man dressed in camouflage rode his bicycle to a county prison near Gettysburg on Thursday, displayed a gun to a guard in the lobby and then fired it several times during a standoff outside before a state trooper shot him, the county prosecutor said.

Adams County District Attorney Shawn Wagner said his preliminary investigation suggests the trooper was justified in shooting the man once, ending a 30-minute standoff in which no other people were hurt.

"All preliminary indications were the police showed restraint," Wagner said. "I'm thankful there were no inmates, no correctional officers, nor civilians nor police officers injured in this. Given the circumstances, we could have had a very tragic situation."

The man was shot in the upper torso and was taken to a hospital trauma unit for treatment, Wagner said.

He said the man carried a backpack, an AR-15 rifle, three magazines and a handgun. He said the investigation into a possible motive was ongoing.

The shooting occurred around 1 p.m. at a prison in a rural area east of Gettysburg.

Wagner said the man fired a weapon six or eight times into the air and onto the ground during the standoff just outside the prison entrance. When the man shouldered the rifle and pointed it toward the entrance, a trooper fired a shot from about 100 yards away, hitting him, Wagner said.

"(The man) did not fire the weapon in the direction of any specific individual, nor did he point it in the direction of any specific individual" before pointing it at the front of the prison, Wagner said.

Authorities didn't release the names of the man or the trooper who shot him.