The Oakland Police Department said the shooting injured a 15-year-old boy, a 29-year-old woman and two men ages 27 and 28.
The victims were taken to various hospitals. All of them are in stable condition.
The shooter attended the party and was known by many guests, according to OPD spokesperson Johnna Watson , who described the shooting as an "isolated incident." Reports indicated there were more than two dozen people at the party.
Police say their primary focus is finding the suspect, who fled the scene before they arrived.
The victims and witnesses speak Mam, but Watson said police didn't have an interpreter available at first.
"Our investigators certainly are making strides. ...we do have some challenges, but we'll certainly overcome those challenges as our investigators work through with the translator, not only with the victims, but with the witnesses that were at the party," Watson said.
Oakland Councilmember Sheng Thao said the incident highlights the importance of diversity in city services.
"Mam translators were needed for the investigation but weren’t immediately available. With Oakland’s diverse population growing, it is vital that we recruit from our diverse communities so that our city services including OPD reflects the community it serves," Thao said in a statement. "Diversity isn’t a talking point, it’s a matter of public safety.”
The East Bay Times reported the incident marks the third shooting in East Oakland since Tuesday evening.
A 61-year-old man was killed and a 17-year-old boy and another man were shot over a five hour time period between Tuesday night and Wednesday morning.
Authorities say they don't believe the shootings are related.
KQED's Ted Goldberg, Julie Chang and Audrey Garces contributed to this report.