Baldwin Park police responded to the 14600 block of Demblon Street at about 10:06 a.m. regarding a gunshot victim.
When police arrived, they found a victim suffering from a gunshot wound to his upper torso. The man was transported to a local hospital, where he was pronounced dead.
The Los Angeles County Sheriff's Department say Gregory Kingsbury, 37, shot and killed his brother and fled in a charcoal gray Nissan Altima, which was later recovered.
Authorities say Kingsbury frequents the Baldwin Park, West Covina and Monrovia areas. He is described as 5 feet 9 inches tall, 220 pounds, with brown hair and green eyes. Authorities say he has a bump on the back of his head from a previous trauma.
Anyone with information on his location, please contact the Los Angeles County Sheriff's Homicide Bureau at (323) 890-5500.