The suspect in the killing of conservative influencer Charlie Kirk at Utah Valley University on Wednesday appears to be "college age", say investigators.

Officials told a news conference they have "good video footage" of the gunman, but are not releasing it yet. They said they have tracked the suspect's movements as he jumped off a roof after the shooting and fled campus into a neighbourhood.

Kirk, who founded conservative youth political group Turning Point USA, was shot in the neck on campus while speaking to students.

FBI special agent in charge Robert Bohls said they had recovered the suspected weapon - a high-powered rifle - in a wooded area near to the scene of the attack and a "footwear impression".

He said they do not think the community is at risk.

Utah Department of Public Safety Commissioner Beau Mason said the gunman "appears to be of college age", and had blended well into the campus environment. 

"We're not releasing many details right now," Mason added. "We will soon. But right now, we're not."

The suspect arrived on campus at 11:52 local time yesterday, officials said - just under half hour before Kirk was shot at around 12:20.

Investigators said he climbed the stairwells up to the roof, and then across the roof to the shooting location. After the shooting, he jumped off of the building and escaped.

Hours after the shooting in the city of Orem, 40 miles (64km) south of Salt Lake City, people gathered near campus, hoping to retrieve vehicles and other possessions left behind as they had fled the scene.

"It's scary," student Brock Anderson told the BBC. "It's unsettling around the campus right now."

Vice-President JD Vance, a close friend of Kirk and his family, is travelling to Utah to pay his respects. 

He and his wife, Usha, cancelled their trip to New York City, where they initially planned to visit Ground Zero and attend a ceremony commemorating the 24th anniversary 9/11. 

After attending a 9/11 memorial service at the Pentagon, President Donald Trump expressed his condolences and said "we're going to be talking about" bringing the country together "very soon".

"You don't replace a Charlie Kirk. He's unique, as you all know... but, we'll do the best we can," he said.

He said he intends to honour Kirk by posthumously awarding him the Presidential Medal of Freedom.

Trump said he would call Kirk's family this afternoon, and that he had been briefed on the investigation.

"They have a virtual manhunt out there," he said. "We'll see what happens. We hope they get him."