A good guy with a gun may have saved lives Saturday night during a shooting in Birmingham, Ala.

Police say that around 10:45 p.m., they received a call that multiple people had been shot at a McDonald's restaurant after an armed man wearing a mask entered the restaurant, WIAT reports. He forced his way inside as an employee was letting a father and his sons out the door and opened fire.

The father was armed and returned fire. The father, one son, and the masked man were shot. The father and son have non-life-threatening injuries. The masked assailant was fatally wounded, police said.

An investigation is ongoing. Police say it is unclear whether the masked assailant intended to rob the McDonald's or was targeting someone inside.

Based on preliminary information, the father who defended himself and others with a gun won't face charges, the report said.