Kirk, widely credited with aiding Trump rally the conservative youth vote, was fatally shot at a college campus in Utah.
Charlie Kirk — one of US President Donald Trump's staunchest allies and prominent conservative activist — was fatally shot at a campaign event at Utah Valley University as he debated members of the crowd.
Videos of the incident circulating on social media show a loud gunshot ring out with Kirk briefly clutching his neck before collapsing in his chair. Attendees at the event scrambled to flee.
Trump announced the news with a post on his Truth Social platform, writing: "The Great, and even Legendary, Charlie Kirk, is dead. No one understood or had the Heart of the Youth in the United States of America better than Charlie."
Kirk was 31 years old.
What happened?
Kirk, who was well known for speaking at college campuses across the US, was at Utah Valley University for the first of several scheduled campus events included in his "America Comeback Tour."
He was taking part in a segment of the tour title "Prove Me Wrong", where he invited students in the crowd to debate him on key political and cultural topics.
Videos have shown that Kirk was debating a student about mass shootings before he was killed.
"Do you know how many transgender Americans have been mass shooters over the last 10 years?” Kirk was asked, before responding, “Too many.”
Kirk was asked again, “Do you know how many mass shooters there have been in America over the last 10 years?” He replied, “Counting or not counting gang violence?” before a gunshot rang out. Kirk collapsed in his chair seconds later.
No one else was shot during the incident, which was attended mostly by college students. Authorities believe the shooter acted alone.
Kirk's wife and two children were present during the attack.
Who was Charlie Kirk?
Kirk was one of the US' most prominent conservative voices, media personalities and a key ally of Trump.
He co-founded Turning Point USA, a nonprofit that advocates for conservative politics on high school and college campuses, when he was just 18 years old.
With his co-founder, William Montgomery, the organisation aimed to take their ideas for lower taxes and limited government to college campuses around the US. They argued their organisation provided a counterbalance to liberal politics that largely dominated US campuses.
Turning Point enthusiastically backed Trump once he clinched the nomination for president in 2016, with Kirk serving as a personal aide to Trump eldest son, Donald Trump Jr, during the campaign trail.
Kirk rose with Trump's campaign to become a recognisable media personality, regularly appearing on TV where he heaped praise on the president and waded in on culture wars. His podcast, The Charlie Kirk Show, hosted guests with outspoken views on cultural topics.
Turning Point saw its donations double and then triple, eventually climbing to $79.2 (72.1 million) in 2022. The organisation now has more than 800 college chapters and a presence on nearly 4,000 high school and college campuses in the US.
The organisation, and Kirk, were credited with playing a key role in mobilising youth voters to help Trump win his second term. Kirk was praised by Republicans for his part in the get-out-the-vote effort, helping register thousands of new voters and winning Trump the state of Arizona.
"The impact he had on young people — reaching them in masses, giving them courage to stand up, to think for themselves, and to fight for freedom — is immeasurable," said Donald Trump Jr. in a post on social media.
Kirk was known for his views preaching free speech, free markets and limited government. He spread anti-transgender views and scepticism over the Covid-19 pandemic.
Several months before his death Kirk said it was, "worth it to have a cost of, unfortunately, some gun deaths every single year so that we can have the Second Amendment".
Reacting to the shooting, some pointed out that Kirk encouraged and acknowledged debate over sometimes conflicting ideas.
"The genuine decency and respect that he showed to other people, even while disagreeing with them, even while they were yelling at him. I don't think I can ever remember ever seeing him respond back to hatred with hate, or with anything other than respect," Utah Senator Mike Lee said in response to Kirk's death.