LOS ANGELES—A man whom police believe is responsible for killing three people and wounding five others, including a 1-year-old boy, in shootings in the Harbor City, San Pedro, and Wilmington areas was in custody Jan. 24.

Dion Johnson, 20, was arrested on Monday, Los Angeles Police Department Capt. Jamie Bennett said at a news conference Thursday morning at the Los Angeles Police Department’s Harbor Area Station.

Charges of murder and attempted murder have been filed against Mr. Johnson, according to the Los Angeles County District Attorney’s Office.

According to police, Mr. Johnson is believed responsible for the following crimes:

• On Sept. 4, 2023, Carlos Loera, 21, and Ashley Guzman, 18, were shot and killed in the 1000 block of 253rd Street in Harbor City. Their 1-year-old child was also struck by the gunfire but survived his injuries.

According to police, the shooting occurred at 6:37 p.m. that day when a gunman approached a vehicle occupied by the three victims and fired several shots at them. Mr. Loera died at the scene and Ms. Guzman died at a hospital. The child was treated at a hospital and released to family members.

• On Sept. 30, 2023, Joseph Saldana, 17, was shot and killed in the 1200 block of North Park Western Drive in San Pedro. According to police, Joseph was shot about 11:30 p.m. that day outside a house party at a residence in the 1200 block of North Park Western Drive.

He was with three other people when one or more suspects approached them on foot and shot them, the LAPD reported.

Joseph was pronounced dead at the scene. The other victims, apparently in their early 20s, were hospitalized in stable condition, according to police.

• On Oct. 2, 2023, a man was shot and seriously wounded in Wilmington.