US authorities have launched a manhunt for the suspected killer of young American conservative activist Charlie Kirk, a staunch ally of President Donald Trump, who was shot dead Wednesday during a public meeting on the campus of a university in Utah.

President Trump has already blamed the "radical left" for the assassination of the man he called a "martyr for truth and freedom."

The 31-year-old conservative podcaster, a poster boy for pro-Trump youth, was shot in the neck while attending a rally for about 3,000 people on the theme of the American "comeback." The killer's motives remain unknown at this time.

"For years, the radical left has been comparing great Americans like Charlie to Nazis and the world's worst criminals and mass murderers. This kind of rhetoric is directly responsible for the terrorism we are experiencing in our country today, and it must stop immediately," the US president accused in a video posted on his Truth Social network.

"My administration will track down all those who contributed to this atrocity and all other political violence, including the organizations that fund and support them," he said.

Before him, several Trumpist figures had described Charlie Kirk as a "martyr" who fell in defense of conservative and Christian values.

A suspect was arrested and released later in the day, according to the head of the Federal Bureau of Investigation (FBI). "Our investigation is continuing," FBI chief Kash Patel posted on social media.

Charlie Kirk's death was captured on videos that quickly circulated on social media.

According to US authorities, the killer fired from a rooftop about 100 meters from the scene.

The president ordered American flags to be flown at half-mast in tribute to the man who was a key player in his last presidential campaign.

The immense White House standard has been lowered.

"Political violence"

Charlie Kirk, a fan of sparring with students, was attending an outdoor event on the campus of Utah Valley University in the west of the country.

Around noon local time, "a shot was fired at Charlie Kirk," who was "evacuated from the premises by his bodyguards," the university wrote on X.

Videos show him, shot in the neck, collapsing into his chair, with screams of panic being heard from the audience.

"I want to be very clear, this is a political assassination," Republican Utah Governor Spencer Cox said at a press conference.

Investigators say the only bullet fired was from the roof of a campus building by a man dressed in black in what appears to be a targeted assassination.

On the left, former Democratic candidate Kamala Harris, who lost in the 2024 election, said that "political violence has no place in America."

Former President Joe Biden also called for this type of violence to "stop immediately," along with other left-wing figures such as Barack Obama, Bernie Sanders, and California Governor Gavin Newsom.

"Fountain of Blood"

Sophie Anderson, 45, told the Daily Mail she was 30 meters from the scene: "He was hit in the neck and collapsed, he was just a fountain of blood."

A native of suburban Chicago, a Christian and gun rights advocate, this father of two dropped out of college to devote himself to activism.

He led a youth movement called Turning Point USA. Co-founded in 2012 by the then 18-year-old influencer, this organization became the largest conservative youth group in the United States within a decade.

It includes an army of enthusiastic activists, some of whom were bussed to Washington for the January 6, 2021, protest that led to the Capitol invasion.

With 6.9 million followers on Instagram and 3.8 million on YouTube, his influence had largely served Donald Trump to seduce young American men by promoting an ultra-traditional conception of the family.

AFP