CHICAGO (CBS) — The U.S. Secret Service has launched an investigation into hate mail sent to the DuSable Museum of African American History in Chicago and its chief executive officer.

The threatening letters targeted President Joe Biden, Vice President Kamala Harris, and the Obamas.

“All of us potential targets for those who want to, you know, spew hate and any threats of domestic terrorism have to be taken seriously,” said DuSable Museum President and CEO Perri Irmer.

So far, a total of six letters have been received since January.

CBS 2 Chicago Staff