The incident happened around 8:50 p.m. Tuesday near California Oak Street and Crinklaw Lane, according to the Simi Valley Police Department.
Investigators say two men were involved in a fight when one of them pulled out a gun and shot the other. The unidentified victim died at the scene.
It's unclear if the two men knew each other or what exactly led up to the fight.
Authorities said the gunman remained at the scene and was cooperating with police.