The shooting happened about 3 a.m. in the 27900 block of Calypso Lane in Santa Clarita.
Officials with the Los Angeles County Sheriff's Department said 51-year-old Anthony Davis had walked over to his next door neighbor's house to complain about a bright light that was shinning into his window. They said an argument began between Davis and the neighbor, 51-year-old Lennie Tracey. Davis was shot twice in the upper torso and died at the scene.
"My mother heard shots and then she heard the victim's wife screaming that he was dead and my mother ran out of the house and saw him and come back and got me," said neighbor Nichole Soto, who tried to administer CPR.
People in the neighborhood said the two men had an ongoing dispute for six years.
Neighbors said Davis had taken out a restraining order against Tracey and set up surveillance cameras after having his home and cars vandalized.
Tracey was booked for murder and was being held on $1 million bail.