Authorities searched on Thursday for the shooter who with one gunshot from a distant rooftop killed conservative activist and Trump ally Charlie Kirk as he spoke at a Utah college event.

Whoever fired the gun on Wednesday then slipped away amid the chaos of screams and students fleeing the Utah Valley University campus. Federal, state and local authorities were searching for an unidentified shooter early Thursday and were working what they called "multiple active crime scenes."

“This is a dark day for our state. It’s a tragic day for our nation," Utah Gov. Spencer Cox said. "I want to be very clear this is a political assassination.”

Two people were detained Wednesday, but neither was determined to be connected to the shooting and both were released, Utah public safety officials said.

Authorities did not immediately identify a motive behind the killing of Kirk, who played an influential role in rallying young Republican voters. But 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.