WASHINGTON: US right-wing activist and commentator Charlie Kirk, an influential ally of President Donald Trump, was fatally shot in the neck on Wednesday (Sep 10) at an event at a Utah university in what the governor described as a political assassination.

Authorities said they still had no suspect in custody as of Wednesday night, about eight hours after the midday shooting at Utah Valley University campus during an event attended by 3,000 people.

The lone perpetrator suspected of firing the single gunshot that killed Kirk, 31, apparently from a distant rooftop sniper's nest on campus, remained"at large," said Beau Mason, commissioner of the Utah Department of Public Safety, at a news conference four hours later.

State police issued a statement on Wednesday night saying that two men had been detained and one was interrogated by law enforcement, but both were subsequently released.

"There are no current ties to the shooting with either of these individuals," the statement said."There is an ongoing investigation and manhunt for the shooter."

In a video message taped in the Oval Office and posted to Trump's Truth Social online platform, the president vowed that his administration would track down the suspect.

"My administration will find each and every one of those who contributed to this atrocity and to other political violence, including the organisations that fund it and support it," Trump said.

Mobile phone video clips of the killing posted online showed Kirk addressing a large outdoor crowd at Utah Valley University in Orem, Utah, around 12.20pm MT (Thursday, 12.20am, Singapore time), when a gunshot rang out.

Kirk moved his hand toward his neck as he fell off his chair, sending the attendees running. In another clip, blood could be seen gushing from Kirk's neck immediately after the shot.

Jeff Long, chief of the university police department, said that he had six officers working the event, and that he coordinated with the head of Kirk's private security team, which was also on site.

Trump ordered all US flags flown at half-staff until Sunday in Kirk's honour.

"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. He was loved and admired by ALL, especially me, and now, he is no longer with us," Trump wrote on social media.

The killing was the latest in a series of attacks on US political figures, including two assassination attempts of Trump last year, that have underscored a sharp rise in political violence.

"This is a dark day for our state, it's a tragic day for our nation," Governor Spencer Cox said at the press conference."I want to be very clear that this is a political assassination."

Kirk's appearance on Wednesday was the first in a planned 15-event American Comeback Tour at universities around the country. He often used such events, which typically drew large crowds of students, to invite attendees to debate him live.

Seconds before he was shot, Kirk was being questioned by an audience member about gun violence, according to multiple videos of the event posted online.

"Do you know how many mass shooters there have been in America in the last 10 years?" Kirk was asked.

He responded,"Counting or not counting gang violence?" He was shot moments later.

FAR-REACHING INFLUENCE

Kirk and the group he co-founded, Turning Point USA, the largest conservative youth organisation in the country, played a key role in driving young voter support for Trump in November.

After winning his second presidential term, Trump credited Kirk for mobilising younger voters and voters of colour in support of his campaign.

"You had Turning Point's grassroots armies," Trump said at a rally in Phoenix in December."It's not my victory, it's your victory."

Kirk had 5.3 million followers on X and hosted a popular podcast and radio program, The Charlie Kirk Show. He had also recently co-hosted Fox & Friends on Fox News.

He was part of an ecosystem of pro-Trump conservative influencers – including Jack Posobiec, Laura Loomer, Candace Owens and others – who have helped to amplify the president's agenda. Kirk frequently attacked mainstream media and engaged in culture war issues around race, gender and immigration, often in a provocative style.

At the White House, staff members, many of them young and admirers of Charlie Kirk, were ashen-faced as news of the shooting spread.

Kirk was married and had two young children.

POLITICAL VIOLENCE ON THE RISE

While the motive for the shooting is unknown, the United States is undergoing its most sustained period of political violence since the 1970s. Reuters has documented more than 300 cases of politically motivated violent acts since supporters of Trump attacked the US Capitol on Jan 6, 2021.

In July 2024, Trump was grazed by a gunman's bullet during a campaign event in Butler, Pennsylvania. A second assassination attempt two months later was foiled by federal agents.

In April, an arsonist broke into Pennsylvania Governor Josh Shapiro's residence and set it on fire while the family was inside.

Earlier this year, a gunman posing as a police officer in Minnesota murdered state lawmaker Melissa Hortman and her husband and shot Senator John Hoffman and his wife. And in Boulder, Colorado, a man used a makeshift flamethrower and Molotov cocktails to attack a solidarity event for Israeli hostages, killing one woman and injuring at least six more.

In 2022, a man broke into Democratic then-House Speaker Nancy Pelosi's home and bludgeoned her husband with a hammer, leaving him with skull fractures and other injuries. In 2020, a group of right-wing militia members plotted unsuccessfully to kidnap Michigan Governor Gretchen Whitmer, a Democrat.

Both Republican and Democratic politicians expressed dismay over the shooting.

"Eternal rest grant unto him, O Lord," Vice President JD Vance, who was close to Kirk, wrote on X.

"I am shocked by the murder of Charlie Kirk at Utah Valley University," Democratic House Minority Leader Hakeem Jeffries said in a statement.