Guys, I don't think the U.S. Marshals are in DC for crowd control. The U.S. Marshals Service is the federal government’s primary agency for fugitive investigations. The Marshals have the broadest arrest authority among federal law enforcement agencies. The Marshals provide assistance to state and local agencies in locating and apprehending their most violent fugitives.

https://www.usmarshals.gov/duties/factsheets/fugitive_ops.pdf