The missing children are: Kay'den Brown, 2; Kase Brown, 4; Kai Brown, 4; and Koen Brown, 5.
The boys were last seen July 1 around 2 p.m. in the 800 block of East P-12 in Palmdale, according to the Los Angeles County Sheriff's Department. Investigators say they are possibly headed to Mojave.
The Palmdale Sheriff's Station said this is a custody issue where the boys were taken by a relative, but they're not sure which family member. Currently, the case is not considered a kidnapping but that could change.
The reason a Missing Persons Bulletin was released is because of the boys' ages, authorities said.
Kay'den is 2 feet tall, weighs 25 pounds and has curly brown hair and brown eyes. He was last seen wearing a white diaper.
Kai is 2 feet tall, weighs 30 pounds and has short brown hair and brown eyes. He was last seen wearing white underwear.
Kase is 2 feet tall, weighs 30 pounds and has brown hair and brown eyes. He was last seen wearing a white diaper. He is diagnosed with Down syndrome.
Koen is 3 feet tall, weighs 40 pounds and has short brown hair and blue eyes. He was last seen wearing white underwear.
Anyone with information is asked to contact authorities or detective J. Munguia at (661) 272-2454.