The video in the player above is from a previous report.
The agency is also offering a reward of up to $20,000 for information leading to the identification and arrest of those responsible.
San Jose teenager Desi Romero was shot and killed at an unsanctioned event on July 25.
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Six others were hurt but have since been released from the hospital.
According to social media posts, a San Jose-based influencer organized the party to celebrate a birthday.
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The Santa Clara County Sheriff's Office called a press conference for 1 p.m. to give an update on the investigation.
Anyone who attended the party or has information about the shooting is urged to contact investigators at 408-808-4431 or SHF.SOTips@shf.sccgov.org.