Four victims were initially pronounced dead following the shooting on Thursday night, and at least four more were hospitalized. The Contra Costa Sheriff’s Office announced Friday night that one of those being hospitalized, identified as 19-year-old Oshiana Tompkins, had died from her injuries.
The home where the party took place, in the affluent town of Orinda, just east of Berkeley, had been rented through Airbnb, according to San Francisco ABC station KGO.
One partygoer told the San Francisco Chronicle that most of the party's attendees were college students. An Instagram post earlier in the week advertised an “Airbnb Mansion Party,” KGO reported.
The owner of the home told the Chronicle that he had rented out the house to a woman who was planning to have a family reunion for about a dozen people.
He told the paper that as the party got underway he began getting calls from neighbors about the level of noise, and that he called police after checking his home security camera and seeing well over a dozen people in the house.
The shootings occurred while the police were still on their way, according to reports.
"When the officers arrived, the encountered at least 100 people running from the home," Orinda Police Chief David Cook told KGO.
Video from the scene showed partygoers running -- and others limping -- away from the residence, as first responders lifted patients into ambulances.
Police on Friday identified the others who had been killed as 22-year-old Tiyon Farley, 24-year-old Omar Taylor, 23-year-old Ramon Hill Jr. and 29-year-old Javin County.
"We are still investigating the scene," Cook told ABC News in an email Friday morning.