There was panic in the battleground state of Nevada on Sunday at Donald Trump's rally.
It was the moment predicted by so many - a threat to the candidate.
Someone shouted "gun", and Secret Service agents rushed the stage, using their bodies as shields and dragging Mr Trump away from the open.
Minutes later, a defiant Mr Trump was back in front of the rally.
"Nobody said it was ever going to be easy for us, but we will never be stopped," roared Mr Trump.
The man was taken away by police - no weapon was found - and he was released without charges.
He told journalists he was holding a "Republicans against Trump" sign.
"I get tackled by all these people, who were just like, kicking me, grabbing me in the crotch and just beating the crap out of me," protester Austyn Crites said.
"I'm very thankful for the law enforcement who was quickly able to come because had they not been there it's possible these people could have strangled me, killed me, right on the spot."
However, there was a different type of fireworks in Philadelphia as Katy Perry joined Hillary Clinton on stage.
But everywhere you go there are reminders that there is lots of hate for Ms Clinton.
"She's a total, complete sociopath. She's been doing it for 35 years," one anti-Clinton protester said.
Ms Clinton is fighting hard in Philadelphia, the major city in the battleground Pennsylvania, a state that could be a decider.
It's been called her electoral firewall - if Mr Trump breaches it he could win the election.
The state has voted Democrat since 1988, but Ms Clinton is losing support. In August, she led Mr Trump by 10 percent.
However, by October this had fallen to 8.6 percent. A few days ago, her lead shrank to 4.9 percent, and on Satuday it's only 2.6 percent.
On Saturday, Ms Clinton urged Pennsylvania voters make her the next president.
But the demographics in Pennsylvania look good for Mr Trump. It's 83 percent white, with only 28 percent holding a college degree. That's core Trump support.
Whatever the real level of threat to Mr Trump, it doesn't matter. His momentum is very real, and he'll use today's chaos as a rallying cry right up until the election.
And a lot of that will be here in Pennsylvania.
If he takes this state, he can take Ms Clinton out.