Former President Donald Trump has been charged with around two dozen counts, including felonies, sources familiar with the sealed indictment told ABC News.

The exact charges remain unknown since the indictment will not be unsealed until Trump appears in court on Tuesday.

The Manhattan district attorney’s office declined to comment.

The Senate sergeant at arms is warning of potential demonstration activity related to the indictment of former President Donald Trump.

"While law enforcement is not tracking any specific, credible threats against the Capitol or state offices, there is potential for demonstration activity," an email obtained by ABC News said.

Capitol Police "is working with law enforcement partners, so you may observe a greater law enforcement presence on Capitol Hill," the email said, adding that there could be "nationwide impacts to Senate state offices."

The Capitol Police declined to comment and the sergeant at arms didn't immediately respond to ABC News' request for comment.

-ABC News' Luke Barr

Former President Donald Trump's daughter, Ivanka Trump, reacted to the indictment on Instagram Friday, writing, "I love my father, and I love my country. Today, I am pained for both."

She added, "I appreciate the voices across the political spectrum expressing support and concern."

Sources familiar with the matter told ABC News the Manhattan district attorney’s office is also investigating a $150,000 payment to Playboy model Karen McDougal, who, like Stormy Daniels, claimed to have had an affair with Donald Trump.

The former president has denied having an affair with either woman and has called the investigation a witch hunt.

McDougal was paid for the rights to her story in August 2016 by American Media, publisher of the National Enquirer, which did not publish it, a practice known as catch and kill.

Michael Cohen, Trump’s former lawyer and fixer, has said he recorded Trump discussing reimbursement to American Media for the payment to McDougal, but the payment was never made.

Trump has not responded to ABC News' request for comment but in a 2018 interview with Fox News, he claimed he wasn't aware of any payment made to AMI to facilitate the alleged hush agreement.

Former President Donald Trump told ABC News over the phone that the indictment is "an attack on our country."

He called it a "political persecution," adding, "They are trying to impact an election."

Trump in a statement Thursday called himself a "completely innocent person" facing "an act of blatant Election Interference."

Trump said, "Our Movement, and our Party - united and strong - will first defeat [Manhattan District Attorney] Alvin Bragg, and then we will defeat Joe Biden, and we are going to throw every last one of these Crooked Democrats out of office so we can MAKE AMERICA GREAT AGAIN!”

Trump's attorneys said in a statement Thursday, "He did not commit any crime. We will vigorously fight this political prosecution in Court."

Trump's son, Donald Trump Jr., said on his podcast Thursday, "This is weaponized justice at its worst."