Former FBI director James Comey found out he'd been fired by President Donald Trump as the news flashed on the television while he was addressing employees.
Mr Comey was removed from his role, effective immediately, over his handling of the end of the Clinton email investigation.
President Trump says he decided to remove him from office following the recommendation of both the Deputy Attorney-General and Attorney-General.
He found out about his firing while addressing bureau employees in Los Angeles, the New York Times reports.
Mr Comey has been criticised for his role in the 2016 election and the investigation into candidate Hillary Clinton's private email server while she was secretary of state.
Ms Clinton has acknowledged that he played a role in her loss to Mr Trump.
"The FBI is one of our nation's most cherished and respected institutions and today will mark a new beginning for our crown jewel of law enforcement," Mr Trump said in a statement.
Mr Trump says the search for a replacement will begin "immediately".
Prior to the announcement, White House press secretary Sean Spicer was asked if Mr Trump still had full confidence in Mr Comey.
"I have no reason to believe...I haven't asked him. I have no asked the president since the last time we spoke about this," he told reporters.
"I don't want to start speaking on behalf of the president without speaking to him first."
What James Comey did wrong
In a letter from Deputy Attorney-General Rod Rosenstein which recommended Mr Comey's dismissal, it says the bureau's "reputation and damage have suffered substantial damage" which has also affected the Department of Justice.
It praises Mr Comey's work ethic, but goes on to say his handling of the conclusion of the Clinton email investigation was indefensible.
"I do not understand his refusal to accept the nearly universal judgement that he was mistaken. Almost everyone agrees that the Director made mistakes; it is one of the few issues that unites people of diverse perspectives."
The letter says Mr Comey was wrong to publicly say the case should be closed and no prosecution taken on "the nation's most sensitive criminal investigation" - an announcement which should have been left for the Attorney-General.
It says "at most", he should have said the FBI had finished its investigation and given its findings to federal prosecutors.
Mr Comey also held a news conference to announce the investigation's conclusion.
"The Director laid out his version of the facts for the news media as if it were a closing argument, but without a trial. It is a textbook example of what federal prosecutors and agents are taught not to do," the letter says.
FBI still investigating Trump campaign links to Russia
Last week, Mr Comey faced up to a Senate judiciary committee mostly about Russia's influence in the election and the investigation into Ms Clinton.
Asked if the Russian government was "still involved" in American politics, Mr Comey replied: "Yes".
At the hearing, Mr Comey confirmed the FBI was still looking into ties between the Trump campaign and Russia.
In his letter, Mr Trump said the termination was effective immediately.
"While I greatly appreciate you informing me, on three separate occasions, that I am not under investigation, I nevertheless concur with the judgement of the Department of Justice that you are no able to effectively lead the bureau."
Mr Comey also told the committee he felt "mildly nauseous" that he'd influenced the election himself having just days before citizens went to the polls on November 8 announced he was looking into Ms Clinton's emails again.
"Look, this is terrible. It makes me mildly nauseous to think that we might have had some impact on the election," he told the committee.
He said he laboured over whether to publicly announce the investigation, but said he wouldn't have changed his decision to do it.
Mr Comey was recently in New Zealand for a top-secret intelligence meeting.
He was hired by former president Barack Obama in 2013 for a 10-year term.
Reaction to James Comey's termination:
- Democratic Representative John Conyers
"Today's action by President Trump completely obliterates any semblance of an independent investigation into Russian efforts to influence our election and places our nation on the verge of a constitutional crisis."
- Republican Senator Lindsey Graham
"Given the recent controversies surrounding the director, I believe a fresh start will serve the FBI and the nation well."
- Democratic Senator Bob Casey
"This is Nixonian. Deputy-Attorney General Rod Rosenstein must immediately appoint a special counsel to continue the Trump/Russia investigation."
- Democratic Senator Chuck Schumer
"Earlier this afternoon, President Trump called me and informed me he was firing Director Comey. I told the president: 'Mr President, with all due respect, you are making a big mistake' ... Given the way the president has fired Director Comey, any person who he appoints to lead the Russia investigation will be concerned that he or she will meet the same fate as Director Comey if they run afoul of the administration."
- Democratic Representative Elijah Cummings, who called for immediate emergency hearings
"There is now a crisis of confidence at the Justice Department and President Trump is not being held accountable because House Republicans refuse to work with us to do our job."
- Fugitive former NSA contractor and whistleblower Edward Snowden
"This FBI director has sought for years to jail me on account of my political activities. If I can oppose his firing, so can you."
- Republican Senator John McCain
"James Comey is a man of honor and integrity and he has led the FBI well in extraordinary circumstances. I have long called for a special congressional committee to investigate Russia's interference in the 2016 election. The president's decision to remove the FBI director only confirms the need and the urgency of such a committee."
- Democratic Senator Richard Blumenthal
"The need for a special prosecutor is now crystal clear. President Trump has catastrophically compromised the FBI's ongoing investigation of his own White House's ties to Russia. Not since Watergate have our legal systems been so threatened."
- Conservative watchdog group Judicial Watch
"This is an important move to restore public confidence in the fair administration of justice at the federal level. Mr. Comey did not seem to understand some of the laws he was asked to investigate and unfortunately politicized his sensitive position as the FBI director."
Reuters / Newshub.
