Police say at least six of their officers have been injured after scores of demonstrators clashed with the authorities outside the Democratic National Committee (DNC) offices in Washington.
Officers in riot gear used pepper spray to disperse the protesters, who were calling for an end to Israel’s military activity in Gaza.
At least one person has so far been arrested, US Capitol Police say.
California lawmaker Brad Sherman was among those who had to be evacuated from the DNC.
“Protestors grew violent, pepper spraying police officers and attempting to break into the building,” he wrote on social media.