Joe Biden strongly denounced political violence on Sunday and urged the country, which is still in shock at the attempted assassination of Donald Trump, to reject "extremism and fury." 

In an Oval Office primetime speech, Biden urged Americans to work toward "national unity" and cautioned that the country's political discourse had grown "too heated" as emotions grew in the last months leading up to the November presidential election.

"There is no place in America for this kind of violence – for any violence. Ever. Period. No exception," he said, adding, “We can’t allow this violence to be normalized."

Biden’s request to Americans to “cool it down” followed Trump's announcement that he would use his speech at the Republican National Convention to bring “the whole country, even the whole world, together.”

Trump told the Washington Examiner, “The speech will be a lot different than it would’ve been two days ago,” noting that the incident was “just setting in.”

In response to the gunman's ability to enter a roof above a Trump campaign rally in Butler, Pennsylvania, on Saturday and fire numerous bullets at the former President from an "elevated position" outside the venue, Biden requested an independent investigation into the incident. The FBI issued a warning on Sunday, stating that since the shooting, there has been an increase in already-heightened online threats of political violence. 

Trump was hurt in the ear during the attack, which is being looked into as a possible act of domestic terrorism and an attempted assassination. Two other people were gravely injured, and a spectator—who was later identified as a former fire chief—was slain.

Read more: Republicans accuse Biden of inciting violence against Trump

“We cannot, we must not go down this road in America,” Biden added, citing a rising tide of political violence that included the assault on the US Capitol, the attack on the husband of the former House speaker Nancy Pelosi, and a kidnapping plot against Gretchen Whitmer, the governor of Michigan.

Biden also gave special recognition to Corey Comperatore, the deceased 50-year-old former fire chief who jumped to protect his wife and kid. Biden called Comperatore a "hero" and offered his family his "deepest condolences".

The 20-year-old suspect, named as Thomas Matthew Crooks of Bethel Park, Pennsylvania, remains a subject of investigation.

The inquiry into how Crooks fired at the crowd, allegedly using an AR-15 that his father had lawfully purchased, was still ongoing more than 24 hours after the attack. After seizing multiple of Crooks' devices, investigators are beginning to put together the conversations he had prior to the incident. Authorities reported that they had found possible explosives in Crooks' vehicle.

Biden on Sunday urged the American public not to make premature assumptions about the motives of the gunman who attempted to assassinate former President Donald Trump.

"FBI is leading this investigation, which is still in its early stages," Biden said. "We don't yet have any information about the motive of the shooter. We know who he is. I urge everyone, everyone, please don't make assumptions about his motives or his affiliations."

He further said he had spoken to Trump on Saturday night and that the two men had a good conversation.

"Last night I spoke with Donald Trump: I'm glad he is recovering," Biden said in a nationally transmitted broadcast. "We had a short but good conversation."

Trump stated that now more than ever, people must unify and not allow "evil to win."

While giving a presidential speech at a Pennsylvania rally, former president and current presidential candidate Donald Trump was shot in what was coined an assassination attempt by Rep. Senator Rick Scott. 

Moments after the shooting, security was able to approach Trump's podium to evacuate him. Trump appeared to have sustained mild wounds, as blood was seen running from the side of his head. 

"In this moment, it is more important than ever that we stand United, and show our True Character as Americans, remaining Strong and Determined, and not allowing Evil to Win," he wrote on his social media network Truth Social.

Meanwhile, the FBI identified Thomas Matthew Crooks, aged 20 and from Bethel Park, Pennsylvania, as the individual involved in what they described as an attempted assassination.

It is worth noting that the Pennsylvania shooting was the first assassination attempt against a US president since 1981 when former President Ronald Reagan was shot and wounded.