President Trump said a group of “thugs” in “dark uniforms” who traveled on a plane to Washington, D.C., is under investigation.

During an interview with Fox News host Laura Ingraham that aired Monday night, the president said “somebody” got on a plane and made a trip to the Republican National Convention last week. While convention meetings took place in Charlotte, North Carolina, Trump and his wife, first lady Melania Trump, delivered speeches at the White House during the virtual prime-time portion of the event.