The first round of charges in special counsel Robert Mueller's ongoing investigation into Russian meddling in the 2016 U.S. election were approved Friday — but it's still not known what they are or who they target.

A federal grand jury in Washington, D.C., approved the charges, CNN reported Friday, citing sources briefed in the matter.

The network said plans were being made to take anyone charged into custody on Monday.

But with the charges still sealed under orders from a federal judge, it's impossible to know who might be involved.

CNN said a spokesman for Mueller's office declined to comment.

The special counsel has been digging into allegations of Russian involvement in the 2016 presidential campaign since May.

Mueller's been focusing on potential collusion between the Trump campaign and Russia.

President Donald Trump is also part of the probe for possible obstruction of justice for his alleged efforts to impede the investigation.

CNN reported that investigators are also scrutinizing Trump and his associates' financial ties to Russia.

In addition to Mueller's probe, three committees on Capitol Hill are conducting their own investigations.