A spokesman with the sheriff's office said the men knew each other and were involved in an on-going dispute.
"That escalated into a physical confrontation that ended in gunfire, and unfortunately, we have a 20-year-old male victim who is dead because of it," said Lt. Mike Crabb with the Orange County Sheriff's Office.
"We're investigating further about what the on-going dispute was about, but this was rather intense for this neighborhood because the suspect actually chased him through the neighborhood several blocks, firing shots at him, and eventually struck him with a fatal wound."
Lt. Crabb also said that the men live in the area. Homicide detectives are interviewing witnesses.
"We are still searching for the suspect and identifying who he is and where he is at right now," Lt. Crabb said.
Lt. Crabb described the fatal shooting as an isolated event and said there is no public safety concern.
The identities of the victim and suspect have not yet been identified.