Authorities said the children's maternal grandparents in Palmdale have custody of the children, who are 6 and 21 months old. The boys' father, Domonic Duncan, Sr., and his mother flew in from Hawaii to see the boys, so the grandparents handed the kids over to the paternal grandmother.
The paternal grandmother invited the parents to have lunch with the boys on Thursday in Carson. When the boys were acting up, 30-year-old Rachel Guerrero took the children outside to calm them down. The trio have not been seen since. Guerrero is reportedly bipolar and schizophrenic, and may have a substance abuse problem.
"We don't know her mental stability right now," said Sgt. Daniel Holguin of the Los Angeles County Sheriff's Department.
Duncan is also missing and is considered a person of interest.
Police say Guerrero frequents the Carson and San Pedro area. Authorities Guerrero and the boys may have been headed to the Dominican Republic, but as of now they are likely in Southern California.
Anyone with information is urged to call Crime Stoppers at (800) 222-TIPS.