Protest live updates: State capitols tighten security; DC locks down; heavily armed man arrested near US Capitol claims 'honest mistake' - USA TODAY

States capitals increased security while Washington, D.C., locked down Sunday ahead of expected inauguration protests.

State capitols across the nation have stepped up security, deploying National Guard units, SWAT teams and extra police officers amid heightened safety concerns following last week's violence at the U.S.

The nation's capital was quiet Sunday amid unprecedented security measures as Americans braced for possible violence ahead of the inauguration of President-elect Joe Biden.

National Guard troops were monitoring Washington, D.C., as well as many state capitals after law enforcement officials warned of possibly violent protests planned nationwide this week by supporters of President Donald Trump, who falsely claims the election was stolen from him.

USA TODAY is monitoring protests and security issues in Washington, D.C., and across the U.S.

Despite tensions in state capitals everywhere, the Virginia Citizens Defense League says it plans on having its voice heard Monday, the pro-gun group's annual Lobby Day at the state Capitol.

The mood was festive at Black Lives Matter Plaza in Washington.

6 riot. They found the security in Washington both reassuring and eerie. Kaye Cole travels often to the city for work.

A woman was arrested after police said she impersonated a law enforcement officer near an inauguration security checkpoint in Washington, D.C., on Saturday morning. .

The suspect drove up to a perimeter checkpoint north of the Capitol Building near Union Station, according to a police incident report that does not give her name. She displayed a military police challenge coin and said she was a law enforcement officer and part of the presidential cabinet, according to the report. .

Secret Service and members of the Florida National Guard stand guard near the Lincoln Memorial on Jan.

Police in Washington, D.C., have arrested a Virginia man who allegedly tried to pass through a security checkpoint with an "unauthorized" inauguration credential,a handgun and more than 500 rounds of ammunition, according to officials. Wesley Allen Beeler, 31, of Front Royal, Virginia, was released on his own recognizance after a hearing Saturday. The Associated Press, citing a law enforcement official who spoke on condition of anonymity, reported that Beeler had a valid credential for inaugural events, though it was not issued by the government.

Beeler told the Washington Post that "it was an honest mistake.” He said he has been working as hired security in downtown Washington and forgot his firearm was in his truck when he left his home in Virginia.

Capitol on Sunday, barricades protected buildings while National Guard members patrolled the grounds and SUVs blocked the streets. To enter Pennsylvania Avenue, the public needed to go through security tents with bag checks and metal detectors

More than 25,000 National Guard members are in place or headed to the city

The National Park Service shut down the entire National Mall, a panoramic 2 miles stretching from the Lincoln Memorial on the west end to the Capitol on the east

The nation's capital is on high-alert with heightened security against threats to President-elect Joe Biden’s inauguration following the deadly pro-Trump insurrection at the U.S

Carney has activated the National Guard to assist state and local law enforcement in keeping the peace if necessary

A  6-foot-tall fence has been constructed around Legislative Hall and traffic has been restricted. Delaware Capitol Police said Capitol buildings "will be secured, and citizens can expect an increased visible law enforcement presence."

The United States Postal Service has temporarily removed blue mail collection boxes in some areas of major cities and state capitols as a security measure in more than a dozen states ahead of the inauguration, USPS said

Michigan, which was targeted by armed anti-lockdown protesters earlier this year and an alleged extremist plot to kidnap its governor, activated its National Guard and was boarding up windows at state buildings. The Texas Department of Public Safety shut down its state Capitol after uncovering new intelligence that prompted the agency to further tighten up security

Across the nation, state capitals were girding for violence