The shooting was reported about 12:30 a.m. in the 1600 block of W. 2nd Street, according to Los Angeles police.
A man and woman were pronounced dead at the scene, and four others were transported to a nearby hospital in critical condition. One of those victims, a man, later died. Police said all the victims are in their early 20s.
Investigators believe the deadly shooting was gang related. They said two suspects pulled up at the party, some words were exchanged and then shots were fired.
Police said the suspects are being sought, but their descriptions were not immediately available.
Investigators were looking into surveillance video in the neighborhood to help catch those responsible.