An activist was arrested after he threw small Russian flags at President Trump on Tuesday during the president's visit for lunch with Republican lawmakers at the U.S. Capitol, police said.

Ryan T. Clayton, 36, of Sterling, Va., was charged with unlawful conduct. A spokeswoman for the U.S. Capitol Police said the incident, which occurred about 1:40 p.m., remains under investigation.

A video shows several flags flying through the air as Trump walked down a hallway with Senate Majority Leader Mitch McConnell (R-Ky.). The flags fluttered in front of Trump but did not appear to hit him. Trump and McConnell continued to walk down a hallway and past a group of reporters without breaking stride or commenting.

The man identified by police as Clayton, dressed in a suit and tie, is heard repeatedly shouting "Trump is treason." As police officers detained him, he shouted his name and affiliation with a group called Americans Take Action, which bills itself as a populist organization.

As he was being arrested, the video shows Clayton alleging in a loud voice that Trump conspired with Russian agents and that "we should be talking about treason in Congress, not about tax cuts."

Trump had been attending the Senate Republicans weekly policy luncheon to talk about tax reform.

Protester Ryan Clayton is taken into custody after disrupting President Trump’s arrival for the Republican policy luncheon on Capitol Hil. (Joshua Roberts/Reuters)