Rep. Sean Duffy (R-Wis.) reported being the victim of a minor assault outside the Capitol Wednesday night.
The congressman told U.S. Capitol Police he was walking from the Longworth House Office Building for votes when "a random individual, unknown to the congressman, began screaming at him and grabbed his arm," according to Duffy's spokeswoman.
A spokesman for Capitol Police said they are investigating. Duffy was unharmed in the incident, according to his office.
Lawmakers have to cross Independence Avenue to get from their offices to the Capitol and have the option of taking the tunnel system underneath the complex to avoid walking outside.
Capitol Police are on patrol on the outside grounds, but lawmakers don't have personal protection.
Tensions have been running high since the government shutdown began on Tuesday, with protesters staging numerous demonstrations around Capitol Hill.