On Wednesday, an aircraft entered limited air space over the rally of US President Donald Trump in Bullhead City, Arizona, resulting in a fighter jet being scrambled to intercept it.

"On October 28, at approximately 1400 MDT, the North American Aerospace Defense Command directed F-16 aircraft to investigate a general aviation aircraft that was not in contact with air traffic control and entered, without proper clearance, the Temporary Flight Restriction (TFR) area around Bullhead City, Arizona", said John Cornelio, a spokesman for the North American Aerospace Defense Command.

The infringing aircraft did not respond to initial intercept procedures but established radio communications after signal flares had been deployed by NORAD aircraft.

"A NORAD aircraft escorted the violating aircraft out of the restricted area without further incident."

On the ground in Arizona, the smaller aircraft was not visible to CNN reporters, but the fighter jet could be heard overhead, leading to a response from the rally crowd and the president himself.

Mr. Trump, apparently caught off-guard by the jet above, said the aircraft was "about four days old," and advertised his military funding.

Mr. Trump said at the sound of the aircraft engines, "I love that sound, I love it." "You have no idea what I went through to get those suckers up there — I had to get the Democrats that money."

For him, he said the jet was "trying to show off " and called the flares being deployed for the President "a little display."

During the rally, US Secret Service agents also responded to the unexpected presence of the jet, with some moving rapidly towards the US President, although they never actually stepped onto the stage.

As the jet could be heard overhead, the crowd cheered loudly, with chants of "U-S-A" and one man yelling, "That's the sound of freedom!"

As part of a final sprint of campaign events leading up to Election Day, Mr. Trump's rally in Arizona came to shore up states he had won four years ago. According to data from Johns Hopkins University, Arizona is seeing an increasing number of coronavirus cases per day. On Wednesday, many rallygoers were seen wearing masks, but not social distances.

The emergence of Arizona, where both Mr. Trump and the running mate of Democratic presidential nominee Joe Biden, Kamala Harris, were scheduled to travel on Wednesday, could throw a major wrench into Trump's electoral hopes as a swing state and provide Mr. Biden with a big lifeline.