Police arrested 31-year-old Ryan Conrad in Torrance at about 4:30 p.m. on the 1400 block of Crenshaw Boulevard.
Conrad is suspected of killing two men at Shadow Ranch Park Wednesday night.
The shooting was reported just after 9 p.m. near Vanowen Street and Sale Avenue. Detectives believe four men, including Conrad, had met at Shadow Park.
Nearby witnesses say it sounded like an argument broke out, followed by gunshots.
Two of the men were shot: one died at the scene and another died at a hospital. A third man who ran off was interviewed by detectives in Riverside County Friday with hopes of learning the reason for the shooting, among other things.
The shooting happened just feet from where a group of teens was playing soccer in the park.
Investigators said one of the victims identified Conrad as the gunman before he died.
"The victim only basically stated the suspect's name," Det. Dave Peteque with LAPD Valley Homicide said. "He was unable to speak after that. He did not give a motive."
Police said Conrad knew both of the victims.