A Manhattan grand jury has indicted former President Donald Trump, making him the first current or former president to face criminal charges.

It was not immediately clear what the indictment was connected to, or what charges Trump will face. The indictment is under seal.

In a statement released Thursday evening, a spokesperson for the Manhattan district attorney's office said, "This evening we contacted Mr. Trump's attorney to coordinate his surrender to the Manhattan D.A.'s Office for arraignment on a Supreme Court indictment, which remains under seal. Guidance will be provided when the arraignment date is selected."

Trump is expected to surrender in New York early next week, sources familiar with the matter tell ABC News.

Speaking to ABC News, Trump called the indictment "political persecution" and "an attack on our country."

"They are trying to impact an election," said Trump, who is running for president in 2024.

"From the time I came down the golden escalator at Trump Tower, and even before I was sworn in as your President of the United States, the Radical Left Democrats -- the enemy of the hard-working men and women of this Country -- have been engaged in a Witch-Hunt to destroy the Make America Great Again movement," Trump said in a subsequent statement. "Weaponizing our justice system to punish a political opponent, who just so happens to be a President of the United States and by far the leading Republican candidate for President, has never happened before. Ever."

Trump has been under investigation by the Manhattan DA's office, which has been probing the $130,000 hush money payment made to Stormy Daniels, the adult film actress who has alleged she had an affair with Trump, which he has long denied.

Michael Cohen, Trump's former lawyer who wrote the check to Daniels in the closing days of the 2016 campaign, went to prison in part over the payment, which federal prosecutors believed amounted to an illicit campaign donation, according to court records.

When Trump reimbursed Cohen for the payment, his company logged the payments as a "monthly retainer" for Cohen's legal services, according to Trump and court documents from Cohen's subsequent plea deal. Prosecutors were considering whether Trump should be charged with falsifying business records, sources say.

"This is all about accountability," Cohen told reporters when he arrived to testify before a Manhattan grand jury earlier this month. Of Trump, he said, "He needs to be held accountable for his dirty deeds."

Trump has long insisted he did "absolutely nothing wrong" and has called the investigation part of a witch hunt by a Democratic prosecutor. An attorney for Trump has said the payment was not meant to protect the campaign, but to protect Trump's family.

"He made this with personal funds to prevent something coming out, false, but embarrassing to himself, his family, his young son," defense attorney Joe Tacopina told George Stephanopoulos two weeks ago on ABC's Good Morning America.

Manhattan District Attorney Alvin Bragg last year won a tax fraud conviction against Trump's namesake company, and its former finance chief, Allen Weisselberg, pleaded guilty to tax evasion -- but until now Trump himself had never faced an indictment.