Charlie Kirk, the CEO and co-founder of the conservative youth organisation Turning Point USA, was fatally shot Wednesday at an event at a Utah college, officials said.

US President Donald Trump said Kirk was shot and killed as he was speaking at Utah Valley University. The shooting quickly drew reaction from leading political figures, including some victims of political violence.

Videos posted to social media show Kirk speaking into a handheld microphone at the university's Sorensen Center courtyard, sitting under a white tent emblazoned with the slogans, “The American Comeback” and “Prove Me Wrong.”

A single shot rings out and Kirk reaches up with his hand as a large volume of blood gushes from the left side of his neck. Stunned spectators gasp and scream. Some run away.

A “person of interest” was in custody Wednesday evening, Utah Gov. Spencer Cox said, though no charges were immediately announced. That person was later released, according to FBI Director Kash Patel.

"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," Trump posted on Truth Social.

"He was loved and admired by ALL, especially me, and now, he is no longer with us. Melania and my Sympathies go out to his beautiful wife Erika, and family. Charlie, we love you!"

Kirk was speaking at an event at Utah Valley University when the attack happened.

Video from the scene showed 31-year-old Kirk speaking under a tent in front of a large crowd when the sound of a single shot rang out.

The footage showed Kirk appearing to collapse in his chair before the camera swiftly moved and the sound of panic began to erupt in the audience.

"Today at about 12:10 a shot was fired at the visiting speaker, Charlie Kirk. He was hit and taken from the location by his security. Campus police is investigating, a suspect is in custody," the university said in a statement on its social media.

A separate university statement quoted by Fox News said the shot had been fired from a long distance, although this could not be verified immediately.

"Shots were fired from a building about 200 yards from the speaker," the statement said."The individual was hit and was taken away immediately by his security personnel. Campus is closed for the rest of the day."

'He fell back'

Former Utah congressman Jason Chaffetz, who was at the rally, told Fox News the shooting had happened during a question and answer session.

"First question was about religion. He went on for about 15-20 minutes. Second question, interestingly, was about transgender shooters, mass shooters, and in the midst of that, the shot rang out," a shaken Chaffetz told the network.

"Now I happened to be watching Charlie. I can't say I saw blood. I can't say I saw him get shot, but as soon as that shot went out, he fell back.

"Everybody hit the deck, everybody... a lot of people started screaming, and then everybody started running."

Kirk had an outsized influence in US politics, helping the rise of Trump's support among younger voters – one of the key factors in the Republican's return to power last year.

With natural showmanship skills, Kirk co-founded Turning Point USA in 2012 to drive conservative viewpoints among young people, turning him into the go-to spokesman on television networks and at conferences for the youthful hard right.

He used his enormous audiences on and YouTube to build support for anti-immigration policies, outspoken Christianity, and viral takedowns of hecklers at his many campus events.

His presence on campuses was seen on the right as a welcome contrast to widespread liberal viewpoints in higher education, but sparked often fierce opposition.

News of the shooting provoked horror across the political spectrum, with senior figures on the right and left paying tribute.

Right-wing media figure Tomi Lahren called Kirk"visionary".

"He's actually opened the door for so many young conservatives to have a career and have, you know, a voice in this business.

California Governor Gavin Newsom – a frequent foil for right-wing figures like Kirk – called the attack"disgusting, vile, and reprehensible".

"In the United States of America, we must reject political violence in EVERY form," he wrote.