BALTIMORE (WJZ) —  Police will be on high alert Saturday for the “Justice for J6” rally at the U.S. Capitol, and officers from Maryland could be called in to help. Possibly hundreds of people are expected to gather in support of those charged in the January 6th riot.

“Last week the Capitol Police Board issued an emergency declaration, which will go into effect about the time of the demonstration and allow the Department to deputize outside law enforcement officers as United States Capitol Police Special Officers,” the U.S. Capitol police said in a statement. “We want to reassure everyone these are temporary measures to ensure everyone’s safety,” said Chief Thomas Manger. “We are extremely grateful for the support we continue to receive from the local community and our congressional stakeholders as we carry out our critical mission.”

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Intelligence suggests extremist groups will be in attendance.

New cameras, on loan from the Department of Defense, have been installed around the Capitol. Security fencing will also return temporarily, but Chief Manager said it will be taken down soon after the event.

Michael Greenberger founded the University of Maryland Carey School of Law’s Center for Health and Homeland Security.  “Domestic terrorism is a very serious threat. We will not always get advanced notice,” he said.

Greenberger is hopeful things will not get out of hand because there is enough advanced notice, and law enforcement is taking this more seriously than in January.

“As a general matter, law enforcement and intelligence agencies have to be on alert. I do not see this Saturday as being of consequence because the lesson was learned on January 6th,” Professor Greenberger told WJZ Investigator Mike Hellgren.

More than a dozen people from Maryland have been charged in the January 6th attack, and many of those cases are still winding their way through the courts.

They include that of Daniel Egtvedt from Western Maryland who allegedly confronted officers inside the Capitol that day. They later threw him out of the building.

The FBI raided the home of defendant Elias Costianes in Baltimore County.

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Matthew Miller is a Howard County teen accused of scaling the Capitol draped in a Maryland flag.

David Blair is accused of attacking an officer with a lacrosse stick that had a confederate flag attached to it.

“They thought it was a free pass. Many of them used the excuse President Trump was cheering us on,” Greenberger told Hellgren. “Many thought they got a get-out-of-jail-free card, but the prosecutions show there are consequences.”

Greenberger fears, even though law enforcement is better prepared, the threat America faces from domestic terrorism is on the rise.

“There are a lot of people in the country who are angry over various things, and if they’re not watched carefully, they can present very serious problems. January 6th was an example of that,” he said.

U.S. Capitol Police arrested a man from California Monday who had a bayonet and machete in his truck — which was painted with white supremacist symbols, including swastikas — near the Democratic National Committee headquarters early Monday morning.

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One Washington, D.C. church group is now calling for Airbnbs and hotels to stop taking reservations for Friday and Saturday.