WASHINGTON (NewsNation Now) — The U.S. Capitol locked down Wednesday with lawmakers inside as violent clashes broke out between supporters of President Donald Trump and police.

An announcement was played inside the Capitol as lawmakers were meeting and expected to vote to affirm Joe Biden’s victory. Due to an “external security threat,” no one could enter or exit the Capitol complex, the recording said. Vice President Mike Pence has been evacuated safely.

Protesters tore down metal barricades at the bottom of the Capitol’s steps and were met by officers in riot gear. Some tried to push past the officers who held shields and officers could be seen firing pepper spray into the crowd to keep them back. Some in the crowd were shouting “traitors” as officers tried to keep them back.

Videos posted online showed protesters fighting with Capitol Police officers as police fired pepper spray to keep them back.

Police told congressional staff members they should evacuate the Cannon House Office Building and the building that houses the Library of Congress. It wasn’t immediately clear what specifically sparked the evacuation.

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Trump’s supporters rallied to bolster the president’s unproven claims of widespread voter fraud. Election officials from both political parties, governors in key battleground states and Trump’s former attorney general, William Barr, have said there was no widespread fraud in the election.

“We will not let them silence your voices,” Trump told the protesters, who had lined up before sunrise to get a prime position to hear the president.

The crowd cheered when he said, “We will stop the steal.” That’s been the rallying cry of protests against the election results.

“We will never give up, we will never concede,” Trump said in his hour-long remarks.

From the Ellipse south of the White House, the protesters marched to the Capitol. Trump said he would be with them. Organizers also rallied Tuesday evening at Freedom Plaza.

Nirav Peterson, who flew in from Seattle to attend the rally, said there would be a groundswell of anger and activism if Trump doesn’t serve another term and said Republicans who don’t back him should face primary challenges.

“People are angry. This isn’t going to go away,” Peterson said as she took video of the large crowd gathered beyond the steel barriers at the foot of the Washington Monument. “You have a huge, huge portion of the people who aren’t going to take it anymore.”

“If they don’t fight, we have to primary the hell out of the ones that don’t fight,” Trump said, calling the Republicans who aren’t siding with him “weak.”

Defying Trump, Vice President Pence said that he does not have the power to discard electoral votes that will make Biden the next president. Pence said in a statement issued minutes before he was to begin presiding over the joint session of Congress.

Footage from Freedom Plaza Tuesday showed groups of protesters waving flags, many without masks. Even as temperatures dropped to the low 40s and a steady rain swept onto the streets, hundreds remained in the plaza into nightfall.

Police reported 12 protest-related arrests on Tuesday and Wednesday for a variety of offenses, including weapons charges, assault on a police officer, simple assault, possessing a stun gun and other violations.

The National Park Service received three separate applications for protests on Tuesday or Wednesday, with estimated maximum attendance at around 15,000 people, said Park Service spokesman Mike Litterst.

Many businesses in downtown D.C. have boarded up their windows.

Bracing for potential violence, Mayor Muriel Bowser has requested a limited National Guard deployment. Bowser asked that local area residents stay away from downtown D.C., and avoid confrontations with anyone who is “looking for a fight.” But, she warned, “we will not allow people to incite violence, intimidate our residents or cause destruction in our city.”

A pro-Trump rally in December ended in violence as hundreds of Trump supporters — some wearing the signature black and yellow of the Proud Boys faction — sporadically fought with anti-Trump demonstrators attempting to bar them from Black Lives Matter Plaza, an area near the White House.

At least 33 people were arrested after the rally and a 29-year-old man was arrested in connection to reported stabbings near the protests.