Orem (United States) (AFP) - Authorities hunted Thursday for a shooter who killed conservative activist Charlie Kirk in an attack that sparked fears of spiraling political violence in the United States.

President Donald Trump lashed out after the killing of Kirk, a powerful voice in conservative US politics at just 31 years old, and he vowed to crack down on those responsible for what he described as “a dark moment for America.”

Kirk was shot in the neck while speaking at an event at Utah Valley University on Wednesday. Video from the scene showed him addressing a large crowd when a single shot rang out.

The father-of-two collapsed in his chair before sounds of panic erupted in the audience.

Students at the university described the shooting as “crazy” and “scary.”

“It makes me feel like I should be very careful about expressing my political ideas,” said Samuel Kimball, a software engineering student, told AFP.

Utah Governor Spencer Cox, a Republican, called the killing a “political assassination” but investigators have not yet made public a possible motive.

Trump, in a somber video message from the Oval Office hours after Kirk’s death, led a chorus of conservative voices suggesting that liberals had contributed to the killing.

“For years, those on the radical left have compared wonderful Americans like Charlie to Nazis and the world’s worst mass murderers and criminals,” he said.

“My administration will find each and every one of those who contributed to this atrocity.”

- ‘Death penalty’ -

The Utah Department of Public Safety said the shooter, dressed in dark clothing, fired from a nearby rooftop. The killer remained at large Thursday morning despite an extensive search by authorities including the FBI.

Two people initially detained for questioning were released after officials determined they had no connection to the shooting.

Cox, the Utah governor, issued a stark warning to the shooter during an emotional news conference.

“I just want to remind people that we still have the death penalty here in the state of Utah,” he said.

Kirk’s killing marks another politically linked death in an increasingly divided United States, and a further instance of gun violence that plagues the country.

Three months ago, a Minnesota man shot dead a Democratic lawmaker and her husband in their home, and Trump survived an assassination attempt during his election campaign in July 2024.

Kirk, who supporters have hailed as a “martyr” for conservative ideals, had an outsized influence in US politics.

He co-founded Turning Point USA in 2012 to drive conservative viewpoints among young people, his natural showmanship making him a go-to spokesman on television networks.

Kirk used his enormous audiences on TikTok, 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.

US politicians from both parties, as well as world leaders, condemned Wednesday’s killing.

“There is no place in our country for this kind of violence. It must end now,” former president Joe Biden wrote on X.

Vice President JD Vance was due to travel to Utah to meet Kirk’s family Thursday, a source familiar with the plans said, after he canceled a trip to New York to mark the ⁹⁄₁₁ attacks anniversary.

No details on the weapon used have been released, but gun ownership in the United States exacts a staggering toll, with about 20,000 deaths a year from shootings – plus another 25,000 deaths from suicides.

Guns outnumber the 340 million people in the country, and attempts to restrict sales fail due to political deadlock as gun activists fiercely defend their Second Amendment rights.