LOS ANGELES -- Two 18-year-old men have been charged with murder in the killing of former “General Hospital” actor Johnny Wactor .

Robert Barceleau and Sergio Estrada were each indicted on Monday in Los Angeles County Superior Court, according to District Attorney George Gasón, who announced the charges at a press conference.

"The passing of this promising young actor, who was at the peak of his career and had so much to contribute to the world, is deeply felt by all of us," Gascón said.

The two men and their two co-defendants, all of whom were taken into custody last Thursday, were scheduled to be arraigned on Monday afternoon. It is uncertain whether any of the defendants have secured legal representation yet. An email sent to the county public defender's office seeking information about the case did not receive an immediate response.

Wactor was shot and killed when he interrupted three thieves stealing the catalytic converter from his car on May 25. Police said the 37-year-old had left work at a downtown LA rooftop bar with a coworker when he saw three men who had hoisted his car. Police said one of them fired at him without provocation and killed him.

Barceleau and Estrada were also both indicted on charges of grand theft and attempted robbery.

Barceleau's charges include special circumstances, including murder during an attempted robbery and personal use of a firearm, which could result in a life sentence without the possibility of parole upon conviction. Estrada's charges carry a maximum sentence of life in prison.

A third individual, Leonel Gutierrez, who authorities believe was with them, was charged with grand theft and attempted robbery. A fourth, Frank Olano, was charged with being an accessory after the fact.

Wactor's death has become a catalyst for some in the city advocating for a more stringent approach to combatting crime.

A group consisting of family and friends calling themselves “Justice for Johnny” held a rally last week urging for more urgency in the investigation, and another Monday morning calling for aggressive prosecution.

Authorities confirmed that this is precisely what is taking place.

LAPD Interim Chief Dominic Choi stated at Monday's press conference that the investigation has been an “ongoing and persistent effort" in a “very challenging case.”

Mayor Karen Bass declared in a statement that “We must continue to take decisive action to enhance the safety of our city.”

Barceleau was being held without the option of bail, and Estrada on a bail amount exceeding $1 million.