Search warrants were executed by the Los Angeles Police Department and the following suspects were arrested:
- Robert Barceleau, 18, of Huntington Park
- Leonel Gutierrez, 18, of Los Angeles County
- Sergio Estrada, 18, of Los Angeles County
- Frank Olano, 22, of Inglewood
Barceleau, Gutierrez and Estrada were booked on suspicion of murder while Olano is believed to have been an accessory to the crime.
Wactor was shot "without provocation" around 3:25 a.m. on May 25, after he ended his shift at a bar and walked to his car with a female co-worker, according to police.
The 37-year-old was confronted by three people who had his car "raised up with a floor jack and were in the process of stealing the catalytic converter," police said in a statement. One of them shot Wactor in the chest as he approached. Just before he was shot, Wactor immediately stepped in front of his coworker to try to protect her, according to his family and friends.
Paramedics rushed Wactor to a hospital, where he was pronounced dead.
MORE: Co-worker who witnessed shooting death of actor Johnny Wactor speaks out
Co-worker who witnessed shooting death of 'General Hospital' actor Johnny Wactor speaks out
Police recently released photos of the suspects and vehicle connected to the murder.
Catalytic converters are popular targets for thieves because they are rich in precious metals that can be resold.
In a press conference Tuesday, Wactor's mother, Scarlett Wactor, urged Mayor Karen Bass and District Attorney George Gascón to strengthen the criminal justice system.
"It needs to start with LA. People watch you from across the country. And this is where change needs to start," Scarlett Wactor said.
She told reporters what the loss of her son has meant to her.
"I'm beginning to sound like a broken record, but grief is my constant companion," she said.
In an emotional press conference in June, Wactor's family and friends pushed for arrests to be made in the case.
"I'm here because one of the best men -- if not the best man -- I've ever known, was tragically and brutally taken from this earth," Wactor's friend, Micah Parker, said at the news conference. "He was taken from his mother, his brothers, his extended family, his friends and his fans."'
Wactor appeared on nearly 200 episodes of "General Hospital" from 2020-22. His other credits included "Westworld," "The OA," "NCIS," "Station 19," "Criminal Minds" and "Hollywood Girl."
ABC News contributed to this report.