LOS ANGELES (AP) — An 18-year-old man has been charged with murder for his role in the off-duty killing of a rookie Southern California police officer during an attempted robbery earlier this month, prosecutors said Tuesday.

Gerardo Magallanes, of the San Pedro area of Los Angeles, also faces charges including shooting at an occupied vehicle and unlawful possession of a firearm while on probation, the LA County District Attorney's Office said in a statement.

It wasn't immediately known if Magallanes has an attorney. He is scheduled to be arraigned Sept. 8.

Monterey Park police Officer Gardiel Solorio, 26, was shot and killed Aug. 8 in a parking lot outside a fitness center in Downey, a Los Angeles suburb.

The gunman got out of a nearby car with a gun drawn and tried to rob Solorio, who tried to get away by putting his car in reverse but was shot five times at close range, prosecutors said.

Carlos Daniel Delcid, 20, was arrested hours after the killing. He has been charged with one count each of murder, attempted robbery and possession of a firearm by a felon with the special circumstance allegation that the murder was committed during a robbery.

Delcid appeared in court last week but didn’t enter a plea and his arraignment was postponed until next month. If convicted, he could face life in prison without the possibility of parole.

A 17-year-old who was believed to be the getaway driver also was arrested and was charged with murder in Juvenile Court.

Solorio joined the suburban Monterey Park Police Department as a recruit in January, graduated from the county sheriff’s academy on July 22 and started field training on July 25.