Houston police say a second suspect, a juvenile, was arrested after Sunday night's shooting.
Police say officer Carl Rodriguez was driving his own vehicle when he spotted two people attacking a person who had just walked out of a convenience store. Police say the officer ordered the suspects to stop. One suspect, 17-year-old Oscar Gaspar, began walking toward Rodriguez and displayed a pistol.
Police spokesman John Cannon says Rodriguez, who remained in his vehicle, feared for his life and shot the teen.
Cannon says the officer took what he thought was the appropriate action to keep the beating victim from additional injury. That person wasn't seriously hurt.