Washington Post video reporter Dalton Bennett was pulled back and knocked down by riot police in downtown Washington D.C., while trying to video tape the arrest of dozens of anti-Trump protesters in Washington D.C.

Protesters wearing all black were arrested as part of an unauthorized march by a group calling itself the “Anti-Capitalist, Anti-Fascist Bloc.” According to a online appeal for marchers, the aim of the march was to “join together and demonstrate how to prevent Trump and his cronies from implementing their program.”

While marching south on 13th Street, protesters overturned trash cans and news racks. At one point, they smashed the windows of a parked, unoccupied limousine and threw a flare inside. After the protest turned east on I Street, marchers began smashing the windows of businesses and the screens of ATMs.

Riot police with batons, mace, and pepper spray arrived and pushed protesters into another line of armored police at 12th & L Streets, where several dozen were surrounded and arrested.

Stephen Ginsburg, senior politics editor for the Washington Post called Bennett’s treatment “unacceptable,” in a tweet.

Top Photo: Police use pepper spray on protesters in Washington, Friday, Jan. 20, 2017, in a confrontation blocks from Donald Trump’s inauguration.