More details are emerging about the so-called "mystery flights" carrying undocumented children from the southern border to Westchester in the middle of the night.

In response to a News 12 inquiry, a Department of Health and Human Services spokesperson said in a statement, “It is our legal responsibility to safely care for unaccompanied children until they can be swiftly unified with a parent or a vetted sponsor. As part of the unification process, our Office of Refugee Resettlement facilitates travel for the children in its custody to their family or sponsors across the country. Over the last week, unaccompanied children passed through the Westchester airport en route to their final destination to be unified with their parents or vetted sponsor.”

A Biden administration official says these flights are legal and are part of the immigration plan of reuniting undocumented immigrant families after former President Donald Trump's "zero tolerance" policy separated families to dissuade people from entering the country illegally.

Republican state Assemblyman Colin Schmitt has concerns about passengers allegedly arriving "in secret" in the middle of the night.

"Quite frankly, these individuals should not have ever been brought to Westchester County Airport," says Schmitt. "No county or local officials, law enforcement or health agencies were notified."

Westchester County Executive George Latimer says the minors were reunited with family in New York City, New Jersey and Connecticut and that they were tested for coronavirus. "All I know is that we're not the only airport going through this. There are a lot of places around the country," said Latimer. Latimer says he has a list of questions that he is hoping to get answered by HHS and will be updating the public when he gets his questions answered.

The flights don't surprise Luis Yumbla, a Port Chester Immigrant Defense board member. The organization reconnects these families. He also says they've been happening for months. "Lately, it's happening more because more people are crossing the border and more people are in the shelters…They're put in groups, and they go on a DHS flight, go to the closest airports where the families are located."