Donald Trump lashed out at the "radical left" on Wednesday after the apparent assassination of his right-wing ally Charlie Kirk, vowing a crackdown after a killing that has sparked fears of worsening political violence in the United States.
Kirk, a powerful voice in conservative politics at just 31 years old, had been dead only a few hours when a somber-looking Trump sat behind his desk in the Oval Office to deliver an ominous message.
"This is a dark moment for America," he said on video posted to his Truth Social website, hailing Kirk as a "martyr for truth."
"For years those on the radical left have compared wonderful Americans like Charlie to Nazis and the world's worst mass murderers and criminals.
"This kind of rhetoric is directly responsible for the terrorism that we're seeing in our country today.
"My administration will find each and every one of those who contributed to this atrocity, and to other political violence, including the organizations that fund it and support it."
Kirk was hit while speaking at an event at Utah Valley University.
Video from the scene showed him addressing a large crowd when the sound of a single shot rang out.
The father-of-two appeared to collapse in his chair before the camera swiftly moved and sounds of panic erupted in the audience.
Investigators said they believe the bullet that killed him had come from a campus rooftop, fired by someone dressed in black, in what appeared to be a targeted killing.
There was confusion over the manhunt, with FBI Director Kash Patel initially tweeting that the "subject" had been detained, before walking that back an hour later.
"The subject in custody has been released after an interrogation by law enforcement. Our investigation continues," he wrote on X.
Illustrating the huge importance of Kirk in Trump's orbit, the 79-year-old Republican ordered flags on government buildings -- including the White House -- to be lowered to half-staff until Sunday.
"No one understood or had the Heart of the Youth in the United States of America better than Charlie. He was loved and admired by ALL, especially me, and now, he is no longer with us," Trump wrote.
Utah Governor Spencer Cox told reporters Kirk's killing was "a political assassination."
Cox, a Republican, appealed for Americans to take a step back from violence as the nation readies to mark a milestone anniversary of its 1776 founding.
"We just need every single person in this country to think about where we are and where we want to be, to ask ourselves: Is this what 250 years has wrought on us?"
- 'He fell back' -
Former Utah congressman Jason Chaffetz, who was at the rally, told Fox News the shooting had happened while Kirk was doing a question-and-answer session with the crowd.
"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 visibly shaken Chaffetz told the network.
"As soon as that shot went out, he fell back," he said. "Everybody hit the deck... a lot of people started screaming, and then everybody started running."
- Turning Point -
Kirk had an outsized influence in US politics, powering Trump's support among younger voters -- a key factor in the Republican's return to power last year.
With natural showmanship, Kirk co-founded Turning Point USA in 2012 to drive conservative viewpoints among young people, turning him into a go-to spokesman on television networks.
He used his enormous audiences on Instagram and YouTube to build support for anti-immigration policies, outspoken Christianity and gun ownership, and to spread carefully edited clips of his interactions during debates at his many college events.
News of the shooting provoked horror across the political spectrum.
"Eternal rest grant unto him, O Lord," Vice President JD Vance posted on social media.
Right wing media personality Tomi Lahren called Kirk "visionary."
Figures on the left also condemned the attack and urged calm.
"There is no place in our country for this kind of violence. It must end now," former president Joe Biden wrote on X.
California Governor Gavin Newsom -- a frequent foil for right-wing figures like Kirk -- called the attack "disgusting, vile, and reprehensible."
Former congresswoman Gabrielle Giffords -- a Democrat who herself survived an assassination attempt -- said she was "horrified" by the attack.
"Democratic societies will always have political disagreements, but we must never allow America to become a country that confronts those disagreements with violence," Giffords said.
Kirk's killing came three months after a Minnesota man shot dead a Democratic lawmaker and her husband in their home.
