Charlie Kirk, a conservative activist and close ally of President Donald Trump who played an influential role in rallying young Republican voters, was shot and killed Wednesday at a Utah college event in what the governor called a political assassination carried out from a rooftop.

Ryan DeVries was attending the event and planned on asking questions on a public forum when the 31-year-old Kirk was shot and killed. The shooter remained at large early Thursday.

"This situation, people definitely feared for their lives," said DeVries. "I could see it in their eyes, I could hear it in their voices. People were crying, people were screaming. It was a nightmare."

The circumstances of the shooting drew renewed attention to an escalating threat of political violence in the United States that in the last several years has cut across the ideological spectrum.

The assassination drew bipartisan condemnation, but a national reckoning over ways to prevent political grievances from manifesting as deadly violence seemed elusive.

Kirk was speaking at a debate hosted by his nonprofit political organization. Immediately before the shooting, Kirk was taking questions from an audience member about mass shootings and gun violence.