Morelos Canseco is interior secretary of Tamaulipas state, home to the city of Nuevo Laredo where the children were abandoned. He told local news media Thursday that police have "evidence that indicates that their parents were kidnapped and that was the reason they were abandoned."
He says authorities are looking into who was behind the abductions. The area is rife with violent drug cartels that have been involved in kidnappings.
Officials have not revealed the children's ages, but local news media report that they range from a few months to about 10 years old.