(NewsNation) — President Joe Biden said there is no place in America for political violence like the attempted assassination of his predecessor.

“It’s time to cool it down,” the president said in an address from the Oval Office Sunday evening.

While investigators don’t know the motive or political beliefs of 20-year-old Thomas Matthew Crooks, who authorities say fired at former President Donald Trump, Biden recounted the basic facts that shocked the nation.

“A former president was shot. An American citizen killed while simply exercising his freedom to support the candidate of his choosing,” he said.

“Politics must never be a literal battlefield and God forbid a killing field. There is no place in America for this type of violence,” Biden added.

He noted that the Republican National Convention begins on Monday, and Republicans will certainly criticize his record as president.

“I’ll continue to speak out strongly for our democracy, stand up for our constitution and the rule of law. That’s how democracy should work. We debate and disagree. But in America, we resolve our differences at the ballot box.” Biden slightly flubbed that sentence, which came out “battle box.”

Biden, while postponing a trip to Austin, Texas, to speak at the Lyndon Baines Johnson Memorial Library, will go ahead with a trip to Las Vegas to speak to the nation’s largest African American and Latino organizations.

He concluded by saying Americans must continue to be the place where the rule of law is respected, and where dignity and fair play are “living, breathing, realities.”

“Hate must have no safe harbor,” Biden added.