The Merced County District Attorney's Office says Josiah Williams was sentenced to six years in state prison for voluntary manslaughter.
Williams had previously pleaded not guilty to murder charges.
Deputies say shots rang out in 2023 at a home on Sunset Drive near Washington Boulevard near Livingston.
19-year-old Liliana Zaragoza was killed.
A second person was shot and hospitalized.
Williams was also sentenced to six years for assault with a semi-automatic rifle, which he will serve at the same time.