Those men were identified Friday as 23-year-old Abraham Fernandez, the boys' biological father, and his father, 52-year-old Louis Mendoza Fernandez, said police Sgt. Bob Dunn. They are from the Houston area and could be headed back, Dunn said.
A nationwide Amber Alert has been issued for a gray 2009 or newer Dodge Caravan with tinted windows and a dent in the right front door. The boys were last seen wearing Buzz Lightyear T-shirts and gray shorts.
Fernandez and the mother were never married, but were living in Texas until several months ago, when the mother moved with the two boys to California, said police Sgt. Rick Martinez.
He did not know why she moved and said detectives are looking into the father's motive.
Detectives are not aware of any custody disputes over the boys or any domestic violence allegations in the family.
"There are a lot of unanswered questions," Martinez said. "We don't know motivation, we don't know of any anger or any problems that may exist, so until we can find these kids and prove that they are safe we won't rest."