LOS ANGELES—A 17-year-old boy Feb. 23 was charged with murder and other counts stemming from a southeastern Los Angeles County shooting spree that left four people dead, while one of the other defendants in the case was charged along with another man of two additional killings, prosecutors announced.

The teen was identified by the District Attorney’s Office as Deair Fleming Delerence, who was charged in juvenile court with four counts of murder and two counts of attempted murder in connection with the two-day killing spree that occurred Feb. 11–12.

In court Wednesday, Deair denied the criminal petition—the juvenile court equivalent of a not-guilty plea.

Gary Garcia Jr., 42, and Timberland Wayne McKneely, 20, were previously charged with the same counts in connection with the shootings, which left three men and a 14-year-old boy dead. They are scheduled to be arraigned Feb. 29 in a Norwalk courtroom on the charges, which include the special circumstance allegations of multiple murders and shooting from a motor vehicle causing death.

Prosecutors announced Thursday that Mr. McKneely has also been charged along with 18-year-old Joseivan Mendoza with the killings of two other men, aged 30 and 28, in Cudahy and an unincorporated area of Los Angeles County on Nov. 24, 2023. Specific details of those shootings were not immediately available.

Mr. Mendoza is also expected to be arraigned Feb. 29. He has not been linked to the Feb. 11–12 killing spree.

“My heart remains with all the victims, their loved ones, and the communities who have been affected by this senseless violence,” District Attorney George Gascón said in a statement. “My office is fully committed to ensuring that justice is served to all individuals responsible for these heinous murders. I join with all Los Angeles County residents in expressing my gratitude for the hardworking members of law enforcement who continue to investigate these horrific murders.”

The four people who died in the two-day killing spree last week are believed to have targeted randomly by the suspects.

Mr. Garcia, Mr. McKneely and Mr. Mendoza could face life in prison without the possibility of parole if convicted as charged, according to Mr. Gascón. The murder charges include a special circumstance allegation of multiple murders and shooting from a motor vehicle causing death.

The first shooting in the killing spree occurred around 11:30 p.m. Feb. 11 in the 6500 block of Bear Avenue in Bell, authorities said. That shooting left 24-year-old Kevin Parada dead. A 29-year-old man was also fired upon, but was not injured, according to the District Attorney’s Office.

Shortly after midnight, another fatal shooting occurred Monday in the 1500 block of East Florence Avenue in the nearby unincorporated Florence-Firestone area. That victim, described as a 27-year-old Hispanic man, was not immediately identified.

Two boys—both Latino—were shot a short time later in the 5000 block of Live Oak Street near Ellen Ochoa Learning Center in Cudahy. One of them, 14-year-old Javier Pedraza Jr. of Cudahy, was pronounced dead at the scene. The second boy—a 13-year-old—was taken in what was described as stable condition to a hospital.

The fourth shooting occurred about 2:40 a.m. Monday in the 6300 block of Santa Fe Avenue in Huntington Park, near Gage Avenue, officials said. That man was not immediately identified, but Huntington Park Police Department Chief Cosme Lozano said he was known to be a local homeless man who was “simply walking down the street.”

According to LASD’s Homicide Bureau Capt. Andrew Meyer, sheriff’s homicide investigators responded to all four shooting scenes, and surveillance video quickly determined that a Honda Pilot SUV was at each location around the time of the attacks.

Sheriff’s officials circulated a law enforcement bulletin, and the vehicle was spotted and stopped the afternoon of Feb. 12 by San Bernardino County sheriff’s deputies, and one suspect—believed to be Mr. Garcia—was arrested and booked on suspicion of murder, Mr. Meyer said.

Investigators were then able to identify the second suspect, who was arrested by a sheriff’s Special Enforcement Bureau team on the morning of Feb. 13 in Compton, according to Mr. Meyer.

Deair was arrested on Feb. 15, sheriff’s officials said.

Mr. Meyer said investigators believe the suspects are gang members, but there was no immediate word on a motive for the killings.