President Donald Trump’s White House sent termination notices to several U.S. Attorneys around the country who had been appointed by Democratic President Joe Biden, a move aimed at cracking down on officials who may disobey directives from the new administration.

In the email, the White House’s deputy director for the office of presidential personnel told recipients, “At the direction of President Donald J. Trump, I am writing to inform you that your position as U.S. Attorney is terminated, effective immediately.”

Though it was not immediately apparent that all of them received the White House termination notices, several U.S. attorneys from Seattle to Maryland have resigned from their positions.

Current and former Justice Department attorneys say that although it is common for U.S. Attorneys to resign following a change in the presidential administration, typically the incoming administration requests their resignations rather than sending them tersely worded termination letters.

More than two dozen of Biden’s appointed U.S. Attorneys remained in their positions as of Wednesday. As of Thursday, their offices said at least three were still employed.

There was no response from the White House. Several requests for comment from the U.S. Department of Justice were not answered.

U.S. Attorney Tara McGrath of San Diego, a Biden appointee, was among those fired. Her office reported late Wednesday that she received notification of her termination from the White House, which also thanked McGrath for her service.

Another Biden appointee, U.S. Attorney Erek Barron of Maryland, sent out a farewell email to the entire office shortly after the termination notices were sent, stating that his tenure “has come to an end.”

“It has been an honor to lead such a talented and dedicated team,” Barron wrote, according to a copy of the email seen by Reuters. He confirmed his departure in a post on LinkedIn on Thursday.

According to a statement sent by email, Ismail Ramsey, the U.S. Attorney for the Northern District of California, has also “concluded his leadership” of the position.

According to a spokesperson for her office on Thursday, Seattle-based U.S. Attorney Tessa Gorman also resigned at the president’s request. Gorman was initially appointed on an interim basis by now-former U.S. Attorney General Merrick Garland and then by the judges in the Western District of Washington.

Late Wednesday, Biden-appointed U.S. Attorney Dena King, the top federal prosecutor for the Western District of North Carolina, announced her own resignation.