Conservative activist Charlie Kirk was killed by a single shot in a targeted attack during an outdoor event Wednesday at Utah Valley University, authorities said.

Kirk co-founded the conservative youth organization Turning Point USA and was a close ally of President Donald Trump.

No one was in custody Wednesday evening as authorities seek a new person of interest in the assassination, according to a law enforcement official who spoke on the condition of anonymity to discuss the ongoing investigation. The Utah Department of Public Safety also confirmed no one was in custody in the investigation into Kirk’s killing.

The shooting comes amid a spike in attacks on political figures in the United States across all parts of the ideological spectrum.

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

Authorities say about 3,000 people attended the Utah college event where conservative activist Charlie Kirk was killed.

The Utah Department of Public Safety said in a statement Wednesday evening that the event was held at an outdoor bowl courtyard on campus known as the university quad. It is a common spot for campus events.