The incident happened around 11 p.m. Saturday night at a party outside of Atwater near Highway 99 and Westside Drive in Merced County. The sheriff's office said a rival gang showed up to a party and gunfire broke out.
The sheriff's office said one teenager and one adult were killed in the incident. One female teenage victim was in critical condition at Memorial Medical Center in Modesto. Two other teenagers suffered non-life threatening injuries in the shooting.
Stay with Action News and ABC30.com for more on this developing story.
Update: One female teenage victim was pronounced deceased at Memorial Medical Center.