Two fetuses were found Friday wrapped in a blanket along a road in Fallbrook, the San Diego County Sheriff's Department said.
The San Diego County medical examiner will determine the cause of death. The fetuses were found by a local resident, who initially thought they were dolls.
The fetuses had reached at least 20 weeks of development, said sheriff's Lt. John Maryon.
The incident is being investigated by the Sheriff's Department homicide detail. Maryon said detectives need help in identifying the mother.
"This would be someone who was recently pregnant and is no longer pregnant and does not have their babies to show," Maryon said.
The fetuses were found along St. Peter's Drive near St. Peter the Apostle Catholic Parish.