Homicide investigators were at the scene of a fatal shooting south of Huntington Park on Monday.
Bystanders on the 2400 block of Palm Place in Walnut Park, an unincorporated area of southeast Los Angeles County, heard gunshots at about 1:45 p.m., according to Sheriff's Lt. John Corina.
When they went out to see what was going on, they found a young man who had been shot lying on the sidewalk, Corina said.
The victim was pronounced dead after deputies and paramedics responded to the scene.
"Now we're in the process of trying to figure out what happened, who shot this young man and why," Corina said.
The deceased appears to be in his late 20s, according to the lieutenant.
Although they haven't confirmed his identity, detectives believe they know who he is and are speaking with people who say they know him.
So far, investigators have learned he has family in the neighborhood and some people around there know him, but he lives elsewhere in the L.A. area.
"They haven't seen him in a while, and then all of a sudden he ends up back over here and now he's shot," Corina said.
The incident could be gang-related, or it could be over something else, the lieutenant said, noting that the victim has "a lot of gang tattoos all over him."
Although some in the area heard gunshots, no one who was at the scene saw anything, Corina said.
Detectives are now canvassing the area in search of any witnesses or surveillance video that could help them identify a suspect.