Authorities arrested three people in connection with the protest after protesters in the crowd began to throw rocks, bottles and tear gas at officers, the Phoenix Police Department said Tuesday.
Masked police officers responded with pepper balls and tear gas in an attempt to "disperse the crowd and stop the assaults," police said. Two people were arrested on charges of aggravated assault and the other for criminal damage, police said.
In a press briefing after the arrests, Phoenix Police Chief Jeri Williams pushed back at reports that the scene outside the rally had grown chaotic.
"All in all, we had a successful celebration," Williams said. "I wouldn’t call it chaos.”
She also defended the police department’s use of force, calling it “absolutely” necessary.
"They had their own gas and they threw it at police. Not our gas," Williams said.
Phoenix Mayor Greg Stanton, who also spoke at the news conference, said protests were mostly peaceful, except for a few disruptions.
“Tens of thousands of people came to downtown Phoenix to participate in our democracy to express their First Amendment rights,” Stanton said. "A very small number of people decided to engage in acts of assault on our police officers ... and that is very very unfortunate."
However, he said the city would examine if the approach used by the police was necessary.
“There’s going to be an after-incident review. We’re going to get all the facts and I’ll have a chance to comment in more detail at that time,” Stanton said, adding that the police department is "willing to look in the mirror" and "change policy appropriately."
Hundreds of people, including fervent Trump supporters and anti-Trump protesters, gathered near the Phoenix Convention Center ahead of the rally, which police characterized as peaceful.
The Phoenix Fire Department said it treated more than 20 people in the crowd for heat-related issues, but there were no serious injuries reported.
Inside, Trump spoke for about 90 minutes to a crowd of 15,000 people, according to the White House.
He spent a large portion of his time inside slamming the media for its coverage of him, but he also acknowledged the crowd outside the convention center.
“You got people outside, but not very many. See this room? You're safe in this room. You're very safe in this room,” Trump told the fiery crowd.