One person seriously injured by gunfire during a demonstration in Salt Lake City

A shooting at a protest in Utah against Donald Trump's policies left one person with "life-threatening injuries," police said, adding that three other people were taken into custody.

The tragedy took place on Saturday afternoon in Salt Lake City. The incident occurred during a demonstration that brought together some 10,000 people as part of events called by several leftist associations aimed at destabilizing the Trump administration.

"We can confirm that the shooting caused a serious injury. The patient has been transported to a hospital with life-threatening injuries," the city police wrote on social media, specifying that one person was arrested.

Police Chief Brian Redd stressed during a press conference that the events leading up to the shooting "were very peaceful," adding that the first person arrested had a gunshot wound and was transported to the hospital.

Two other people involved were also detained, he added. "At this time, there is ... no ongoing threat to the public," Redd continued. It is still too early to say whether the shooting was politically motivated, he detailed.

Mayor Erin Mendenhall said "this act of violence does not define" Salt Lake City, a Democratic stronghold in the Republican state of Utah. "The purpose of today's rally was a powerful and peaceful expression until this event and that cannot be overshadowed or silenced by a single act intended to do harm," she stressed, insisting on the eagerness to protest Trump after the presidential election, something that has been tough to swallow for many in the Democratic Party.