Arrests made in killing of off-duty Monterey Park officer.

Officer Gardiel Solorio was killed outside a Downey gym earlier this week. (Courtesy Photo)

DOWNEY - A 20-year-old man and a teenager are behind bars in connection with the fatal shooting of an off-duty Monterey Park police officer during what the district attorney called an attempted robbery in Downey -- and the adult is tentatively scheduled to be arraigned Thursday on murder and other charges.

Carlos Delcid, 20, is tentatively scheduled to be arraigned in Downey on one count each of murder, attempted robbery and being a felon in possession of a firearm. According to jail records, he was arrested around 9:30 p.m. Monday, roughly six hours after the shooting that killed Officer Gardiel Solorio, 26.

The murder charge includes a special-circumstance allegation of murder during a robbery.

Delcid will face a maximum sentence of life in prison without the possibility of parole if convicted as charged, according to Los Angeles County District Attorney George Gascón, who has vowed not to seek the death penalty against any defendants.

A 17-year-old suspect was also arrested for allegedly acting as the getaway driver, Gascón said during a Wednesday afternoon news conference. That suspect, who was not identified, is being charged in juvenile court, and the exact charge or charges were not immediately clear.

The off-duty officer was in his vehicle in the parking lot of an LA Fitness gym in the 12700 block of Lakewood Boulevard around 3:30 p.m. Monday when Delcid allegedly got out of a car nearby and approached Solorio "with a gun drawn in what appeared to be an attempted robbery," the district attorney said.

"Officer Solorio attempted to flee by backing up his vehicle when the suspect fired multiple times," Gascón said. "The defendant then returned back to the vehicle where a juvenile was behind the wheel and they fled the scene."

Solorio was found unresponsive in the seat of his car, and was pronounced dead at the scene, according to Downey police.

Funeral arrangements were still pending for Solorio, a rookie officer just weeks out of the academy. Monterey Park Police Department Chief Kelly Gordon called his killing "a senseless act of violence."

Gordon said at a Tuesday afternoon news conference that Solorio, who grew up in Bell Gardens and graduated from Cal State Los Angeles with a degree in criminal justice, joined the department as a recruit in January, and had just graduated from the sheriff's training academy on July 22 before beginning his field training on July 25.

"Although his time with (the department) was very short, we all knew from the moment we met him that he had the heart of service and was going to be a great officer," Gordon said.

"And I could tell that from the moment he walked in and did our first introductions in my office. The family and department are grieving right now, and this is an especially difficult tragedy. It's a senseless act of violence. He was only 26 years old. I don't know about all of you, but I have children that age. So to me this is particularly difficult."

Gordon added that training staff at the sheriff's academy told her Solorio was "hard-working, dedicated and took every aspect of training seriously," and that he was family oriented.

"The `why' in the biography he wrote was to be a good role model for his nephews, and he really wanted to make an impact on the community," Gordon said. "His classmates shared that Officer Solorio had all the characteristics of a great officer -- he was humble, dedicated, selfless and hard-working, but even a better person. He brought laughter and joy to many of us."

A solemn procession involving officers from the Downey and Monterey Park police departments and Downey Fire Department escorted Solorio's body to the Los Angeles County Coroner's Office on Monday night.

Solorio is survived by his parents, brothers, sisters and fiancée.

His fiancée and one of his sisters attended the Wednesday news conference when the charges against Delcid were announced.

"It's a tremendous loss. It's a loss of life," Gordon said earlier. "In law enforcement, but especially in the Monterey Park Police Department, we're a family. That's the bottom line. We have worked very hard to build a culture within our department that we take care of each other. This is a tragedy. This is a tragedy for his family, but this is a tragedy for the Monterey Park Police Department as well."

On Wednesday morning, the flag at the Monterey Park Police Department was flying at half-staff and the department had received numerous floral arrangements for the fallen officer.

On a GoFundMe page established to help cover expenses for family to attend his funeral, Solorio's sister-in-law, Wanda Marie Lane Solorio, wrote that it was his "lifelong dream" to be a police officer.

"His dream of becoming a police officer after years of hard work and dedication had finally come to fruition, when life was abruptly taken away due to a senseless act of violence," she wrote. "He was taken from his family way too soon. He was and has always been true American success story."

She said Solorio was the youngest of 13 children, and the family is hoping to raise money so all of his brothers and sisters can attend his funeral.

As of Wednesday afternoon, the family had raised more than $16,000.

"(He) was a first generation college graduate, and the first in his family to become a police officer and brother in law enforcement,"  Wanda Marie Lane Solorio wrote.