"This is everywhere. Every community, every town, every state," one of the suspect's neighbors said. "It's going to be everybody's neighbor, everybody's classmate. It's not at all unusual anymore."

Officials said that 22-year-old Tyler Robinson of Utah has been arrested in connection with Charlie Kirk's death.

The Utah trade school student faces formal charges next week from an act of violence widely seen as a foreboding inflection point in US politics.

A 22-year-old Utah man who was booked on murder charges in the assassination of Charlie Kirk held deep disdain for the conservative activist’s provocative viewpoints and indicated to a family member that he was responsible for the shooting.

Yet as Kirk's supporters continue to pay tribute to him, senior US government figures are threatening action against anyone praising the death of the controversial right-wing activist - a testament to the climate of political division and polarisation in which his killing took place.

Mr. Kirk, 31, the founder of a right-wing youth movement, was shot while speaking at Utah Valley University on Wednesday.

In high school classes in Spanish Fork, Utah, chatter spread fast Wednesday, as students learned of the shooting and began to wonder if Kirk would live or die. A cellphone ban meant many students didn’t learn of Kirk’s fate until the final bell — pushing tough conversations in class to the next day.

Tyler Robinson's family played a role in helping turn him in to police as the suspect in conservative speaker Charlie Kirk's assassination at Utah Valley University.