The incident happened last week on a sidewalk at the end of an alleyway near the intersection of Santa Monica Boulevard and Orlando Avenue.
The Los Angeles County Sheriff's Department on Wednesday confirmed arrests were made in the case, releasing a special bulletin on Facebook detailing those arrested.
The suspects have been identified as 26-year-old Keymaurie Clark, 18-year-old Briana Threets, who are both from Oakland, and two juveniles both aged 15.
Surveillance shows the suspects, one of them armed with an assault rifle and another a handgun, approaching the victims and demanding their property, authorities said.
One of the victims was struck in the face with a handgun by the suspects.
Two victims were robbed at gunpoint in the video, and a third victim was robbed at gunpoint while walking on the sidewalk as well.
Suspects armed with apparent assault rifle rob trio of victims in West Hollywood: Surveillance video
"A man walking on the sidewalk interrupted the robbery and the suspects demanded his property and he complied," the department said in a news release at the time.
The robbers made off with a wallet, jewelry and an unspecified amount of cash.
Officials say the suspects fled the scene in a Dodge Charger driven by one of the juveniles.
During the investigation, detectives discovered that the suspects had been arrested by Beverly Hills police on April 26 for armed robbery.
West Hollywood detectives believe their may be more victims and they are working with surrounding agencies to identify more victims.