US President Donald Trump on Tuesday made the shock decision to fire his FBI director James Comey, the man who leads the agency charged with investigating his campaign's ties with Russia.
The New York Times reported that the FBI Director learned of the news while speaking to employees in Los Angeles.
"As he spoke, TV screens began flashing the news," the paper reported.
The FBI has been investigating Russia's alleged intervention in the 2016 election which delivered Trump the White House - an investigation which Mr Comey confirmed included looking into potential links with Trump's campaign team.
White House Press Secretary Sean Spicer told reporters the president made the decision in response to recommendations from his Attorney General and the deputy Attorney General.
A search for a new FBI director was to begin "immediately," the White House said in a statement.
James Comey placed himself in the media spotlight last year when, days before the 2016 election, he advised congress of fresh investigations into Hillary Clinton's use of a private email server during her time as Secretary of State.
Earlier investigations, concluded in July, had not resulted in charges.
Nothing came of the new investigation, but Clinton later said it was a significant factor in her surprise loss last November.
Mr Comey last week testified before a Senate committee, telling members the thought that he had influenced the election made him feel “nauseous”.
WATCH: Comey 'nauseous' at thought he swayed US election
In a memo, Deputy Attorney General Rod Rosenstein said he could not defend Comey's handling of the case, stating it was wrong to announce the FBI's conclusions in July.
Mr Rosenstein also said it was wrong of Comey to release "derogatory information" about Clinton in the July announcement, in which Comey said Clinton and her colleagues were "extremely careless".
In a letter following reciept of the memo, Trump told Comey: "You are hereby terminated and removed from office, effective immediately".
"While I greatly appreciate you informing me, on three separate occasions, that I am not under investigation, I nevertheless concur with the judgment of the Department of Justice that you are not able to effectively lead the Bureau," Trump's letter read.
In testimony to a congressional committee in March, Mr Comey confirmed the FBI was investigating Russia's alleged interference in the 2016 elections, including potential ties to the Trump campaign.
The explosive testimony in the House Intelligence Committee - the first public hearing into both controversies - came as Trump sought to steer the news focus by calling the Russia issue, which has been a cloud over his November victory, "fake news".
In his letter, President Trump wrote: "It is essential that we find new leadership for the FBI that restores public trust and confidence in its vital law enforcement mission."
Senator Richard Burr, chair of the Senate intelligence committee investigating potential Russian ties, said he was "troubled by the timing and reasoning" of the president’s decision to fire Mr Comey.
The decision “further confuses and already difficult investigation” he said.
“Director Comey has been more forthcoming with information than any FBI Director I can recall in my tenure on the congressional intelligence committees. His dismissal, I believe, is a loss for the Bureau and the nation.”
FBI directors are appointed for a single 10-year term. The 56-year-old Comey, who is popular among rank-and-file agents, was appointed four years ago.
His dismissal will raise questions about Trump's motives.
It will also prompt parallels with Richard Nixon's decision to fire his FBI director, an event that plunged his presidency deeper into crisis.
Calls for a special prosecutor
The US Senate's top Democrat said he told President Donald Trump it was a "big mistake" to fire FBI chief James Comey amid a probe into Russia's alleged interference in last year's election.
"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,'" Senate Minority Leader Chuck Schumer told reporters.
Schumer joined several of his Democratic colleagues in calling for an independent prosecutor or commission to investigate claims of Russian interference, as well as possible collusion between Trump's campaign team and Russian officials.
Democrats - already angry that Congressional inquiries have been hamstrung by Republicans' willingness to defend Trump - worried that the FBI's investigation may also be in jeopardy.
"Congressional Republicans cannot possibly disagree now: the only fix to this mess is an independent commission with subpoena power," said Brian Fallon, a former Justice Department and Hillary Clinton spokesman.
During testimony to Congress in March, Mr Comey flatly rejected an explosive claim from Trump that he was wiretapped by his predecessor Barack Obama.
Republicans pointed to Comey's recent misstatement to Congress about a Clinton aide forwarding emails as a possible reason for his dismissal.
"Given the recent controversies surrounding the director, I believe a fresh start will serve the FBI and the nation well," said Senator Lindsey Graham.
"I encourage the president to select the most qualified professional available who will serve our nation's interests."
