Josh Duhamel and Arnold Schwarzenegger have led celebrities in speaking out over Charlie Kirk's death.

On Wednesday, the right-wing political activist and media personality was shot and killed while speaking at an event at the campus of Utah Valley University. He was 31. A manhunt for the suspect remains underway.

In a statement, U.S. President Donald Trump confirmed Kirk had died.

"No one understood or had the Heart of the Youth in the United States of America better than Charlie," he wrote on his Truth Social platform. "He was loved and admired by ALL, especially me, and now, he is no longer with us."

Following the shocking news, Duhamel took to Instagram to condemn the shooter.

"RIP Charlie Kirk. Please remember, no matter what your political beliefs, that this man had a wife and two beautiful children who no longer have him. Please pray for this madness to stop," he urged.

In addition, Schwarzenegger declared that "politics has become a disease" in the U.S.

"But don't listen to the pessimists who say there is no cure. There is a cure. It is inside of us," the actor and former Governor of California posted on X. "We must find our better angels and walk back from the extremes. If we can't agree on anything else, we must find agreement that we don't solve our debates with violence. This is a horrible tragedy. May it also be a moment for everyone to rediscover their humanity."

Elsewhere, Schwarzenegger's ex-wife, Maria Shriver, called on all citizens to "condemn political violence" and former talk show host Rosie O'Donnell expressed her disbelief over the tragic shooting.

"No just no - do not become the murderer - this is wrong on every level - #werallamericans," she posted on Instagram.

A number of high-profile political figures commented on Kirk's death too.

Former U.S. President Barack Obama insisted "this kind of despicable violence has no place in our democracy", while former Vice President Kamala Harris noted she was "deeply disturbed" to learn of the incident.

"Political violence has no place in America. I condemn this act, and we all must work together to ensure this does not lead to more violence," she wrote on X.

Kirk is survived by his wife Erika. The couple shared a three-year-old daughter and a 16-month-old son.