An Alabama man was shot and killed for apparently walking too slowly, said police.
Jackson said Penn is now being held in the Bullock County Jail on murder charges.
According to officials, Penn went to a store to purchase food, but when he stopped to allow Allen to cross the street, he felt that Allen was taking too long.
Jackson said Allen was walking near a gas station when Penn pulled up in his car. Penn then got out of the car and began arguing with Allen before shooting him eight times.
Allen was pronounced dead at the scene, officials said.
When police arrived at the gas station, Penn already fled the scene.
Union Springs is located about 45 miles outside of Montgomery, the state capital.
Other details about the incident were not immediately provided by police.