Charlie Kirk, 31, a right-wing activist and close ally of President Donald Trump, was fatally shot during an event in the western US state of Utah. This is what we know.
Utah Valley University
Mr Kirk, the head of the largest conservative youth movement in the United States, which he co-founded in 2012 at the age of 18, was speaking around noon on the campus of Utah Valley University.
Dressed in a white t-shirt with the word "Freedom" across the front, Mr Kirk sat in a chair under a tent as he answered questions from the large audience gathered around him.
The event was the first of about 15 scheduled across the country through the end of October.
A gunshot, then screams
Former Utah congressman Jason Chaffetz, who was at the event, told Fox News that Kirk was responding to a question about "transgender shooters, mass shooters, and in the midst of that, the shot rang out."
Mr Kirk collapsed and was then rushed away on a stretcher by his security.
"As soon as that shot went out, he fell back," Mr Chaffetz said.
"Everybody hit the deck... a lot of people started screaming, and then everybody started running."
Manhunt ongoing
According to local authorities, the shot came from the campus, possibly from a rooftop, and the shooter was wearing dark clothing.
The university initially said that the shooter was at large, but a few hours later, FBI Director Kash Patel announced that a suspect had been arrested.
That person was later released after questioning, Patel said, meaning the search for the shooter is still ongoing.
Trump announces Charlie Kirk's death
Mr Trump announced Mr Kirk's death, writing on his Truth Social platform: "The Great, and even Legendary, Charlie Kirk, is dead."
On the other side of the political spectrum, Democratic figures also condemned the shooting, including Kamala Harris, who said that "political violence has no place in America."
Trump vows crackdown
Although a suspect has not yet been identified, Mr Trump linked rhetoric from the "radical left" to Mr Kirk's killing and vowed to carry out a crackdown.
"This kind of rhetoric is directly responsible for the terrorism that we're seeing in our country today," he said in a somber four-minute video, seated at the Resolute Desk in the Oval Office.
"My administration will find each and every one of those who contributed to this atrocity, and to other political violence, including the organizations that fund it and support it," the US president said.
