Heavily armed policed are continuing to search for a suspect in the fatal shooting of influential conservative activist Charlie Kirk during a busy event at Utah Valley University.

Authorities say the suspect fired a single shot from a nearby rooftop, hitting Kirk in the neck as he was speaking at the outdoor student event.

The 31-year-old founded Turning Point USA, a group that seeks to spread conservative ideas on American campuses, when he was still a teenager.

President Donald Trump called Kirk a patriot and said his death was a “dark moment for America.”

In a video post, Trump said he was “filled with grief and anger at the heinous assassination of Charlie Kirk”.

Officials say six police officers were working security at the event – which attracted at least 3,000 people to the campus – along with private security hired by Kirk.

Video taken at the scene shows students running for cover as the gunshot rang out at 12:20 local time (18:20 GMT). No-one else was shot at the event.

On Wednesday, law enforcement initially gave conflicting answers about whether the suspect, who dressed in all black, had been caught.

Two people were taken into custody, but police said they were released and “there are no current ties to the shooting with either of these individuals”.

One man, George Zinn, was released after being charged with obstruction of justice. The other suspect was released with no charges filed.

“There is an ongoing investigation and manhunt for the shooter,” the Utah Department of Public Safety said in a statement on Wednesday night.

They said they believed the incident was a “targeted attack”.

“The shooter is believed to have fired from the roof of a building down to the location of the public event in the student courtyard.”

Hours after the shooting, people gathered near the campus, hoping to retrieve vehicles and other possessions they left behind as they fled.

“It’s scary,” said student Brock Anderson. “It’s unsettling around the campus right now, like I’m just trying to walk home, and it’s just unsettling.”

Nearby people piled more than a dozen flower bouquets in front of a school sign, in tribute to Kirk.

Utah Valley University will remain closed until Monday with all classes, both in-person and virtual, suspended.

BBC Verify has confirmed the authenticity of several videos of the shooting which have been posted online.

One video shows students crowded around a white tent emblazoned with the words, “THE AMERICAN COMEBACK” and “PROVE ME WRONG”.

Students flee as Charlie Kirk is shot while speaking to a crowd of hundreds

Kirk, who frequently held debates and speaking events on university campuses, was addressing the crowd and discussing gun violence in the US in the moments before he was shot.

“Do you know how many transgender Americans have been mass shooters over the last 10 years?” an audience member asked.

“Too many,” replied Kirk.

The questioner then said there had been five in 10 years and asked Kirk how many mass shooters there had been in that time.

“Counting or not counting gang violence?” Kirk replied before shots rang out.

Witnesses described their horror at realising that Kirk had been shot.

“It’s a little surreal. Especially then. It felt like a dream,” a first-year student named Gavin told CBS News, the BBC’s US partner.

“Everyone started praying… Then, we started running.”

Deseret News reporters Emma Pitts and Eva Terry described witnessing the attack.

“I’ll never get the image out of my head,” Pitts said. “It looked like a fountain of blood came out of his neck. His body went limp and then his eyes closed.”

She added that she was surprised that “nobody scanned our equipment, nobody scanned our bags, there was no security like that”.

Kirk’s wife and two children were at the event, according to Oklahoma Senator Markwayne Mullins.

Lawmakers from across the US expressed anger over the shooting and condemned political violence.

In a video message from the Oval Office that Trump shared on social media, he hailed Kirk as “a patriot who devoted his life to the cause of open debate and the country that he loves so much”.

He called him a "model for truth and freedom” and went on to blame his death on “radical left political violence”, although authorities have not yet identified a motive behind the attack.

He also pledged to "find each and every one of those who contributed to this atrocity and to other political violence”, and ordered that all US flag on federal properties be flown at half-mast.

Utah Governor Spencer Cox called the attack a “political assassination” and suggested that the killer could receive the death penalty.

“This is a dark day for our state, it’s a tragic day for our nation,” he said, adding that he was in touch with the White House and FBI.

The attack shocked Americans, and led to statements being issued by every living former US president, as well as world leaders including UK PM Keir Starmer, and the leaders of Argentina, Italy, Canada and Israel.

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

Republican Congressman Mike Kennedy told BBC News that Kirk will be remembered as a champion for free speech, and that his death “did not silence Charlie Kirk’s voice, and he will continue to be heard and registered”.

Intimidation and violence does not work against American citizens, he says, and “we’ll continue to move forward with our constitutional privilege of freedom of speech and promoting that as Charlie did throughout his whole life”. (BBC)