A Tennessee National Guardsman is facing prosecution in the shooting of two of his superiors at an armory outside a U.S. Navy base north of Memphis.

The sergeant's first appearance in federal court could come Friday.

Maj. Gen. Max Haston is the head of the Tennessee Guard. He says a major and a sergeant major were wounded in Thursday's attack at the armory just outside Naval Support Activity Mid-South in Millington.

Both were expected to be out of the hospital soon.

A law enforcement official briefed on the case said the sergeant — whose name wasn't released — had been disciplined before he opened fire. The official spoke on condition of anonymity because he wasn't authorized to discuss the case publicly.

Other Guard members detained the shooter before police arrived.