The FBI said it stood by its earlier recommendation that no criminal charges were warranted against Democrat Hillary Clinton for using a private email server for government work, lifting a cloud over her presidential campaign two days before the US election.
FBI Director James Comey made the announcement in a letter to Congress, saying the agency had worked "around the clock" to complete its review of newly discovered emails and found no reason to change its July finding.
"During that process, we reviewed all of the communications that were to or from Hillary Clinton while she was secretary of state," Mr Comey said. "We have not changed our conclusions expressed in July."
A law enforcement source said that, for now, the conclusion closes the FBI probe of Mrs Clinton's email practices.
Mr Comey informed Congress of the newly discovered emails more than a week ago, throwing the race for the White House into turmoil and eroding Mrs Clinton's lead over Republican candidate Donald Trump in the final stretch before Tuesday's vote.
"We're glad this issue is resolved but for the record, this could easily have been learned before 1st letter was sent," Mrs Clinton spokesman Brian Fallon wrote on Twitter.
Republicans, however, did not ease up on their criticism of Mrs Clinton.
"She simply believes she's above the law and always plays by her own rules," House of Representatives Speaker Paul Ryan said in a statement, arguing that Mrs Clinton's use of a private email server "compromised our national security".
The latest emails were discovered as part of a separate probe of former Democratic US Representative Anthony Weiner, the estranged husband of Clinton aide Huma Abedin.
Mr Weiner is the target of an FBI investigation into illicit text messages he is alleged to have sent to a 15-year-old girl in North Carolina.
Meanwhile, Mrs Clinton holds a four-point lead over Republican Donald Trump in the final NBC-Wall Street Journal poll.
The NBC-Wall Street Journal poll showed Mrs Clinton leading Mr Trump by 44% to 40%.
Libertarian Gary Johnson was at 6% and Green Party Candidate Jill Stein was at 2%.
Mrs Clinton's lead shrank from 11 points over Mr Trump the last time the poll was conducted in mid-October, before the FBI said it was reviewing new emails in its investigation of the former secretary of state.
The poll also showed Mrs Clinton with a 12 percentage point lead over Mr Trump - 51% to 39% - among people who have said they have voted early.
Earlier, Mr Trump was rushed off stage by security agents at a rally in Reno, Nevada, last night after a false alarm as someone in the crowd shouted "gun" during scuffles with a man who held up a 'Republicans against Trump' sign.
The incident occurred as Mr Trump and Mrs Clinton crisscrossed the United States a late push to win over undecided voters.
Two security agents seized Mr Trump by the shoulders and hustled him backstage as police officers swarmed over a man in the front of the crowd and held him down and searched him before escorting him away with his hands behind his back.
Mr Trump, seemingly unruffled, returned to the stage and continued his speech after a short time, saying "Nobody said it was going to be easy for us" and adding "We will never be stopped".
After being released, the man who was apprehended told CBS News Reno affiliate KTVN-2 that he was a Republican supporter who attended the rally to express his opposition to Mr Trump.
"I came here with this sign expecting boos ... But it was just a sign," Austyn Crites (above) said.
Mr Crites said when he took it out, the crowd began to attack him, choking and beating him before "someone yelled about a gun".
After being held for questioning and security and background checks, Mr Crites said he was released, and that the police "did their job".
He said he wanted to contrast US President Barack Obama's reaction to a protester during a rally a few days ago, in which he urged the crowd to respect the protester, with Mr Trump's, saying he wanted "people to understand" the difference.
Donald Trump was hustled off stage at a rally in Reno, Nevada in a false 'gun' alarm pic.twitter.com/X8InExPVg9
— RTÉ News (@rtenews) November 6, 2016
"I have nothing against Trump supporters," Mr Crites said.
"We are all registered Republicans and support many of the same candidates for local offices. I have serious concern against Trump," he added.
The Secret Service confirmed that the incident erupted when an unidentified individual in front of the stage shouted "gun".
"Secret Service agents and Reno Police Officers immediately apprehended the subject. Upon a thorough search of the subject and the surrounding area, no weapon was found," the Secret Service said in a statement.
The incident began when Mr Trump noticed what he considered a heckler. Seconds later people near the stage began pointing at someone in the crowd near the front, and agents took Mr Trump away.
In a statement, Mr Trump thanked the Secret Service, Reno and Nevada law enforcement for "their fast and professional response".
Meanwhile, in Philadelphia, pop singer Katy Perry performed at a Clinton rally.
"When your kids and grand kids ask you what you did in 2016, when it was all on the line, I want you be able to say you voted for a better, stronger, America," Mrs Clinton said.
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Early voting began in September and the data firm Catalist estimates more than 30 million ballots have been cast in 38 states.
There are an estimated 225.8 million eligible US voters.
Meanwhile, both campaigns have adjusted travel schedules for the next two days to states where they saw opportunity.
While Mr Trump prefers large-scale rallies, Mrs Clinton has filled her campaign schedule with targeted appearances meant to court voters in specific demographics.
