Police said one person has life-threatening injuries and was taken to a hospital. An arrested man also had a gunshot wound.

Salt Lake City police said they have taken three people into custody after a shooting near the “No Kings” march downtown Saturday evening left a man with a “critical” gunshot wound.

Saturday marked the first full day of Marines on duty in Los Angeles, one week after protests against Immigration and Customs Enforcement raids ignited in LA and spread to other cities across the U.S., including New York City, San Francisco, Boston, and Austin, Texas.

Meanwhile, more than 2,000 “No Kings Day” protests were held across the U.S. on Saturday to protest the Trump administration and to counterprogram the military parade in Washington, D.C., organizers said. More than 5 million people participated, according to organizers.

The demonstrations remained peaceful in almost all cities, but as the evening grew in Los Angeles, tensions escalated between police and protesters.

The injured man was seen collapsed on State Street with emergency responders providing care to him, directly in front of the Liberty SKY apartment complex.

The motive for the shooting and the events that led up to it remained under investigation, police said. Preliminarily, a news release said, the department believes the shooting “involved four people,” which included the critically injured victim.

A man was seen being loaded onto a stretcher by Salt Lake City Fire; he appeared to be the same man officers had handcuffed. The news release said police pursued “one of the involved parties and took him into custody near 200 East and 100 South.”

He was taken to a hospital with “serious injuries resulting from a gunshot wound,” police said, and he remains there under guard. At a news conference Saturday night, Salt Lake City Police Chief Brian Redd said police do not know who shot the man.

Redd said two other individuals were taken into custody later. He did not elaborate on why they were detained.

Police said they heard shots fired at about 7:56 p.m. near 151 S. State St.

Salt Lake Tribune journalists saw protesters running away from a location near the Wallace F. Bennett Federal Building. A Tribune photographer heard officers yelling “Gunman!” and “Man with rifle!” as they swarmed into a parking garage between 100 South and 200 South on State Street.

A video shared with The Tribune by witness Kris Pendleton captured the sounds of shots being fired and the crowd’s frightened reactions.

Organizers were yelling instructions, telling people to move north of the federal building. On social media, Salt Lake City police said, “We are asking people to leave to leave the demonstration safely and orderly.”

The Police Department estimated there were 4,000 people gathered at Pioneer Park before the march to the Bennett Federal Building began. The department had increased that estimate to 10,000 during the march.

Pendleton said he and his wife got to the protest late and were catching up to the back of the march when he heard a loud bang about 10 feet away.

After a second bang, he said, he turned and saw “a guy about 10 to 15 feet away from me in a yellow vest, and he was shooting somebody.”

He said the man in the vest “seemed like someone who knew what they were doing. Maybe it was an armed security guard or a police officer.”

“I was kind of deer in the headlights,” Pendleton said, “and my wife grabbed my arm and said, ‘We need to run.’”

They darted toward a parking garage and saw another man with a gun running past them toward the shooting.

By Salt Lake City Tribune