Ryan Ramos is believed to have been taken by his father, 46-year-old Lonnie Ramos, during a custody exchange between the man and his estranged wife in front of the wife's house, according to Orange County sheriff's Lt. Hal Brotheim.
Lonnie Ramos allegedly shot his wife and then fled with his son, Brotheim said.
The boy's mother is expected to survive her injuries, according to Brotheim.
Lonnie Ramos is described as being a white man, about 6 feet 3 inches and 180 pounds. He is believed to have rented a 39-foot 2005 Fleetwood Providence purple and gold motor home Wednesday with California license plate No. 5EGW556, Brotheim said.
The Orange County Sheriff's Department is asking anyone with information to call (714) 628-7170 or 911.