Members of the Proud Boys brawled with police officers in Washington, D.C., late Tuesday as pro-Trump protests against the certification of President-elect Joe Biden’s victory began ahead of a congressional vote. Video from the scene showed dozens of members of the group facing off against police, whom they accused of betraying the Constitution. The clashes reportedly kicked off after the Proud Boys tried to force their way through a police line at Black Lives Matter Plaza and officers pushed them back. “You lost both sides of support,” one man yelled. “We had your fucking back, but we ain’t got your back no more!” he said, noting that he and other members of the group have military training. “You better have our back, or we’re gonna fucking show you!” he said as another man could be heard yelling that “heads are gonna roll.”

At one point, several members of the group were seen lunging at police officers, only to be forced back as the officers pepper-sprayed them. Police said at least six people were arrested throughout Tuesday’s demonstrations, with charges including assault on a police officer. It was not immediately clear if any of the arrests stemmed from the Proud Boys' skirmishes. The clashes came after the group’s leader, Enrique Tarrio, was banned from the city ahead of Wednesday’s “March for Trump” rally. President Donald Trump has repeatedly called on his supporters to flood the streets for the rally, which is meant to bolster his unfounded claims that he was the rightful winner of the Nov. 3 election. The rally coincides with a congressional vote that will seal Biden’s victory.