Essex County Prosecutor's Office spokeswoman Katherine Carter says Jessica Moore died from her injuries at 3:20 p.m. Saturday. Moore had been hospitalized in critical condition after the shooting just after midnight.
Police say the shooter was a man who was denied access to the party, then left and returned with a handgun.
Police say that in addition to Moore, four others, who have not been identified, were hospitalized with non-life-threatening injuries. One has since been released.
Police say the shooter remains at large. They're offering a $10,000 reward for information leading to the suspect's capture.