A U.S. citizen has been arrested after border officials thwarted an alleged child smuggling attempt at an Arizona port of entry, U.S. Customs and Border Protection (CBP) announced Tuesday.

According to CBP, at about 11:30 p.m. on Thursday, Aug. 29, CBP officers at the San Luis, Ariz. Port of Entry stopped a vehicle being driven by a 28-year-old female U.S. citizen for a secondary inspection.

During the inspection, the woman reportedly told CBP officers that two children in the vehicle were family members.

However, CBP found that there was no family relationship between the woman and the two children, ages 11 and eight, and that two birth certificates presented by the woman for the two minors, while legitimate, did not belong to the children.

The two children, who CBP says were Mexican citizens, indicated to the officers that they were given sleep sedatives prior to the smuggling attempt in an effort to evade detection.

“Our CBP officers prevented this child smuggling attempt utilizing their experience and inspectional skills,” said Chris Leon, Director of the San Luis Port of Entry. “CBP remains committed to upholding our U.S. immigration laws.”

CBP officers arrested the woman for alleged violation of U.S. immigration law and seized the vehicle.

A report published last month by the U.S. Department of Homeland Security (DHS) Inspector General revealed that the federal government has lost track of hundreds of thousands of unaccompanied migrant children who have crossed the U.S.-Mexico border since 2019.

The report showed that approximately 32,000 unaccompanied migrant children failed to show up for scheduled immigration court hearings, meaning their whereabouts are unknown to federal authorities.

That figure is compounded by an estimated 291,000 migrant children — more than half of the total number of unaccompanied minors encountered at the border from 2019 to 2023 — who were not issued court dates, preventing federal authorities from verifying the children’s well-being at immigration court hearings.