An Alabama police officer is being investigated for allegedly shooting and killing a 68-year-old man, authorities said.

A Muscle Shoals police officer fatally shot Ronald Parrish at around 5 p.m. Sunday while responding to an unspecified call in a residential area, according to a statement from the Alabama Law Enforcement Agency. The agency said that police encountered Parrish, who allegedly had a knife, and shot him when he refused to put it down.