Investigators released few details about the additional suspects. One man, 21-year-old Brandon Acuna, is already in custody in connection with the sailor's death. Police declined to specify Acuna's level of involvement in the fatal shooting.
It's unclear if police know the identities of the other possible suspects.
Curtis Adams, 21, was driving south on I-15 with his girlfriend about 2:20 a.m. Saturday when they saw a man standing next to a white vehicle near the north Interstate 5 transition in Logan Heights, police said.
The couple pulled over to help, and Adams was immediately shot after getting out of his vehicle, police said. Adams' girlfriend called 911, and the sailor was rushed to a hospital where he died.
Family members said Monday that Adams' decision to help a fellow motorist didn't surprise them in the least, and was a reflection of his unselfish nature.
Both Abrams Jr. and Adams' brother, Kadeem Adams, said the Navy man was always willing to take that extra step to help others.
"He always wanted to do great things. He always wanted to help people," Abrams Jr. said. He added later, "...You have to be really brave to live like that."
Soon after the shooting, the California Highway Patrol put out an alert that a similarly described white vehicle was stopped on north I-5 near 32nd Street, and that a man was seen walking away from the area.
A San Diego police officer located a man, later identified as Brandon Acuna, on nearby Newton Avenue. Acuna was questioned and arrested on suspicion of murder and burglary.
During the last three years, Acuna has pleaded guilty to a handful of misdemeanor charges that included driving without a license, possessing methamphetamine and, most recently, carrying a concealed dirk or dagger, according to court records.
He received probation and was fined in each case.
Police believe two other people may have been involved in Adams' death, and that the trio of suspects was also involved in a car burglary that escalated to a shooting about 10 minutes before the killing.
Police said in that incident a man was shot at after he came upon people who were trying to break into his vehicle on Boundary Street in Mount Hope.
Adams followed in the footsteps of his father, uncle and brother when he chose to enlist in the Navy in 2016. He was a steelworker with Amphibious Construction Battalion 1, and was stationed at Naval Amphibious Base Coronado.
He's also a first-generation American. Desmond Abrams Jr., a cousin, said Adams' parents both immigrated to New York from the West Indies region. Abrams Jr. said Curtis was simultaneously proud of his cultural heritage and to call the United States home.
"He was always proud of our roots, our background, but we're all Americans at the end of the day," Abrams Jr. said. "He's a good example of that."
This article is written by Lyndsay Winkley from The San Diego Union-Tribune and was legally licensed via the Tribune Content Agency through the NewsCred publisher network. Please direct all licensing questions to firstname.lastname@example.org.