The Office of Special Counsel has determined that six White House aides violated the Hatch Act by using their government Twitter accounts to engage in political activity.

In response to complaints filed by Citizens for Responsibility and Ethics in Washington, the government watchdog said in a letter Friday it issued warning letters to the six White House aides after determining they broke federal law.

The aides are Madeleine Westerhout, executive assistant to the president; Alyssa Farah, press secretary for Vice President Mike Pence; Jacob Wood, deputy communications director for the Office of Management and Budget; Raj Shah, White House principal deputy press secretary; Jessica Ditto, White House deputy communications director; and Helen Aguirre Ferre, the former director of media affairs.

Complaints were also filed over tweets from four other administration officials: White House press secretary Sarah Sanders, White House deputy press secretary Lindsay Waters, Office of Management and Budget Director Mick Mulvaney, and White House deputy press secretary Hogan Gidley.

However, the Office of Special Counsel said those four did not violate the Hatch Act.

The Hatch Act prohibits federal employees from using their offices to campaign for or against political candidates and restricts certain political activities of executive branch employees.

The tweets in question from Westerhout, Farah, and Wood included the "MAGA" hashtag, an abbreviated form of President Trump's campaign slogan, "Make America Great Again."

“Under the Hatch Act, tweeting a campaign slogan of a current candidate for partisan political office constitutes political activity,” the watchdog wrote in a letter to CREW.

Shah also tweeted a message that included a link to the Republican National Committee’s research, which was shared by Ditto.

Shah’s tweet was considered a violation of the Hatch Act because it “highlighted research done by a political party and provided a link to the party’s website and its research,” according to the Office of Special Counsel.

In the case of Ferre, the Office of Special Counsel said she made the header photo on her official Twitter account an image that included “Make America Great Again” in text. Ferre, however, left the White House and subsequently deactivated the account.

Westerhout, Farah, Ditto, Wood, and Shah deleted their posts once they learned they were in violation of the Hatch Act.

[Also read: Sarah Sanders violated the Hatch Act by tweeting photo with Kanye West, says ethics group]