Steven Hans Dunkel, Matthew Scott Riley, Michael John Blankenship and Rudy Javier Madrid were arrested for murder on Monday.
Investigators believe the suspects could be responsible for other armed robberies, specifically involving underground casinos.
Last week, a shooting occurred at a nightclub in the 2200 block of Cahuenga Boulevard. About 30 people were inside at the time, many of whom were able to escape.
Investigators said two men wearing ski masks entered the establishment during an illegal poker game. The security guard brandished a gun and was fatally shot by one of the suspects, police said.
"One of the suspects basically shoots him right as he walks in the door," LAPD Det. Richard Moakley told reporters at the scene last week. "This may have been like a botched robbery attempt."
Police said all four of the suspects' homes were searched where evidence was found linking them to the shooting.
"Detectives believe the two assault rifles identified during the incident have been recovered as well as other evidence linking the suspects to the crime," said LAPD in a statement.
The county medical examiner identified the victim as 32-year-old Anthony Rivas.
Meanwhile, police are asking the public's help in identifying additional victims in this case.