RENO – Donald Trump was rushed off stage Saturday night during a campaign rally here as security officials swarmed, but the candidate emerged back on stage after a few minutes and finished his speech.

Some kind of a disturbance had occurred in the front of the room where Trump was speaking. He put his hand above his eyes to peer out into the crowd. As he did so, a security official rushed to Trump’s side and escorted him off stage. People near the front of the room suddenly scattered as U.S. Secret Service and uniformed officers jumped the barricades to apprehend an unidentified man.

Trump later concluded his rally without further incident. It was not immediately clear what the cause of the disturbance was. CNN, citing “a law enforcement official,” reported that no weapon had been found and that no eyewitnesses reported seeing a gun.

The GOP presidential nominee later released a statement thanking the Secret Service and local law enforcement for their “fast and professional response,” adding that “nothing will stop us – we will make America great again!”

Meanwhile, a press bus carrying reporters covering Democratic vice presidential nominee Sen Tim Kaine’s stops in Florida was hit at high speed, according to reporters traveling with the senator. There were no immediate reports of injuries. Kaine was several cars ahead of the press bus, according to reporters in his motorcade.

Earlier in the day, Hillary Clinton’s campaign announced she will campaign in Michigan on Monday, as polls show her once-comfortable lead in the state eroding and as Trump eyes it as a potential way to come from behind in the hunt for electoral votes.

That announcement from the Clinton campaign came as Trump also rejiggered his itinerary, making plans for last-minute stops in Virginia, where Clinton has led but Republicans are catching up.

The GOP nominee spent Saturday hopscotching the country, rallying with supporters in North Carolina, as well as Florida, Colorado and Nevada – and he announced plans to visit Minnesota, a traditionally Democratic state where polls showing him trailing by about five points. In his speech in Nevada late Saturday, Trump attacked elections officials for allowing a predominantly Hispanic early voting site in the Las Vegas area to stay open for “hours and hours.”

President Barack Obama will also campaign in Michigan on Monday, suggesting that Democrats see danger signs there. Clinton will be in Grand Rapids, Obama in Ann Arbor. Former president Bill Clinton will make a stop in Lansing on Sunday.

“There are just three days left in this most consequential election,” Clinton told a cheering crowd of about 10,000 an open-air rally and concert in Philadelphia on Saturday night.

Clinton noted the millions of people of have voted early and urged Pennsylvania voters to help “send a message” about American values and ideals.

“I believe they are standing up for a hopeful, inclusive vision of America and I’m asking you to stand up for that same vision,” Clinton said.

Over the last two weeks much of Clinton’s focus has been on Florida and North Carolina, as well as Nevada, where early voting is now winding down.

But her campaign manager Robby Mook, conceded to reporters on Saturday that “we have seen tightening in the Midwest generally this cycle, and we are taking that seriously.”

Clinton communications director Jennifer Palmieri told reporters Saturday that in addition to a previously announced stop in Manchester, New Hampshire, on Sunday night, Clinton will add a rally in Cleveland earlier Sunday. On Monday in addition to Michigan, Clinton will add a midnight rally in Raleigh, North Carolina. Another large evening rally had also been announced for Philadelphia that night.

Palmieri said that Khizr Khan will speak at the New Hampshire rally. Khan is the father of fallen soldier Humayun Khan, whose challenge to Trump over the Republican’s proposed ban on Muslim immigration was among the most memorable moments of the Democratic convention.

Trump’s focus on Saturday night was Nevada, where polls show the race tied.

Campaigning in Reno, Trump denounced a decision by elections officials to keep open an early voting site “for hours and hours.”

Early voting totals in Clark County, Nev., which encompasses Las Vegas, topped 57,000, according to local officials. A supermarket doubling as an early-voting site in the county was allowed to stay open for two additional hours on Friday night as thousands of people remained in line to vote. It is customary for state elections officials across the country to authorize keeping a polling site open later if there are long lines at closing time.