RELATED: Rival gangs involved in 'bloodbath' at Airbnb in Orinda: Sheriff
In a statement, the District Attorney's Office says the investigation is ongoing.
LeBraun Wallace, Jaquez Sweeney, Jason Iles, and Shamron Mitchell were arrested on Thursday, accused of murder.
Devin Williamson was also arrested on Thursday. Investigators said he was the promoter of the party.
RELATED: 5 suspects arrested in connection with deadly shooting at Orinda house party, officials say
Williamson was facing a slew of charges, including being an accessory.
Five people died and several others were injured a shooting at the rented Orinda mansion.
One investigator called it a "bloodbath" unlike anything he had ever seen and that many of those who attended the party were armed.