Officers responded to the west side of the Rio San Gabriel riverbed and the 105 freeway around 8:50 p.m. after receiving reports of shots fired in the area.
When they arrived, they found three men suffering from gunshot wounds. All three men died at the scene.
It's unclear what sparked the shooting but police said it "appeared to be an isolated incident."
As of Sunday afternoon, no arrests have been made and information on a suspect(s) has not been released.
Anyone with information is urged to contact Downey Det. Roberts at 562-904-2386. You can also send an email to eroberts@downeyca.org.