Potential explosive devices addressed to the homes of former President Barack Obama and former first lady Hillary Clinton were detected and intercepted by the U.S. Secret Service, which has launched a criminal investigation into the incidents.

“The packages were immediately identified during routine mail screening procedures as potential explosive devices and were appropriately handled as such,” the Secret Service said in an emailed statement Wednesday. “The protectees did not receive the packages nor were they at risk of receiving them.”

A U.S. official said the package addressed to Clinton, which was intercepted Tuesday, was a “functional explosive device.”

Investigators believe the explosive is linked to one found Monday at the compound of liberal billionaire George Soros.

The official wasn’t authorized to publicly discuss an ongoing investigation and spoke on condition of anonymity.

The FBI’s New York field office said in a tweet that its Joint Terrorism Task Force “has engaged with our federal, state and local partners to investigate” the package sent to the Clintons.

Nick Merrill, a spokesman for Hillary Clinton, said in a tweet that “nothing got to any home.”

The package sent to Obama was addressed to Washington, D.C., and discovered Wednesday morning.

Local police and the FBI are investigating.

Reporting from Bloomberg News and The Associated Press was used in preparing this article.