Investigations are ongoing following the assassination attempt of Donald Trump during a rally in Pennsylvania on Saturday.
A spectator was killed and two others were seriously injured.
US President Joe Biden, has called for Americans to come together, saying we need to "lower the temperature" in politics.
He's also ordered an independent security review into the attack at the Pennsylvania rally on Saturday.
The shooting left the former president with a bloody ear, while a man attending the rally was killed and two others were injured.
Addressing the nation from the Oval Office Joe Biden on Sunday said assassination attempt on Donald Trump is "contrary to everything we stand for as a nation".
"There's no place in America for this kind of violence, for any violence, ever. No exceptions.
"We can't allow this violence to be normalized.
"You know, the political record in this country has gotten very heated. It's time to cool it down".
Taoiseach Simon Harris, has described as alarming the increase in political violence across the globe, referencing the assassination attempt on the Prime Minister of Slovakia in May.
What we saw last night from Pennsylvania was frightening and wrong. It is a relief that former President Trump is safe and survived the assassination attempt. Our hearts are with the innocent spectators killed and critically injured. There can be no place for political violence.
— Simon Harris TD (@SimonHarrisTD) July 14, 2024
The US Secret Service is investigating how a gunman armed with a rifle was able to get close enough to shoot and injure Donald Trump.
Matt Shoemaker, Former intelligence officer at the Defence Intelligence Agency, says there may have been a communication problem when it came to security arrangements.
"From my perspective, this looks like this may have been a failure on the law enforcement, the second-tier level.
"The reason why is because the communication between local law enforcement and secret service is oftentimes delayed, and in these sorts of situations, time is of the essence."
Meanwhile, Donald Trump is expected to make his first public appearance since the assassination attempt at the Republican party's National Convention, which starts in Milwaukee today.