The Ronald Reagan Presidential Library postponed a book signing for conservative commentator Ben Shapiro on Wednesday, after fellow right-wing media figure Charlie Kirk was shot and killed at a speaking event earlier in the day.

“The Ronald Reagan Presidential Foundation and Institute is saddened to hear of events that took place today at Utah Valley University. Our prayers are with Charlie Kirk’s family and friends. As a mark of respect, we are cancelling our program and book signing with Ben Shapiro this evening,” read a statement posted to the event page of the library in Simi Valley, Calif.

The statement said a new date for the event would be announced “shortly.”

Two prominent figures in conservative media, Shapiro and Kirk had overlapping circles.

Shapiro mourned Kirk, the co-founder of Turning Point USA, in a post on the social platform X, saying he is “utterly stunned and heartbroken and sick to my soul today” after Kirk’s death on a Utah college campus.

He recalled meeting Kirk, who died at age 31, when he was just 18 years old.

Shapiro said he remembered thinking Kirk was “a young man so eager and determined that I immediately turned to a friend and said, ‘That kid is going to be the head of the RNC one day.’”

“Charlie became even bigger and more important than that,” Shapiro continued. “It was a privilege to watch this principled man stand up for his beliefs and create the single most important conservative political organization in America. But more importantly, Charlie was a good man, a man who believed in right and wrong, who stood by his Biblical values.”

“All of us will miss him, and I can’t imagine the pain of his beautiful young family, and we must all pray for them. And we must pick up the baton where Charlie left it, fighting for the things he believed in so passionately. And we must fight for a better America – an America where good people can speak truth and debate passionately without fear of a bullet. I weep for Charlie’s family, and I weep for my country today. Most of all, I weep for Charlie,” Shapiro wrote.

Kirk was killed while speaking at Utah Valley University. He was struck by a gunshot to the neck and died shortly afterward.

The FBI announced Wednesday evening that a person of interest is in custody.

Trump announced Kirk’s death on social media and ordered flags to be lowered to half-staff through Sunday.