Tensions soared and police ultimately dispersed crowds with tear gas at the huge anti-Trump protest outside the Phoenix Convention Center on Tuesday night, where Trump was inside raging about the news media’s coverage of his administration and dog-whistling his defense of white supremacy at a campaign-style rally. Contrary to Trump’s lie that only a few protesters were outside, many thousands of people had shown up to demonstrate peacefully and condemn the president’s rhetoric and agenda.

Mayor Greg Stanton said officials would examine whether excessive force was used by the city’s police.

The police said they only responded with force after protesters threw water bottles and other objects at them, an account that was disputed by witnesses. The Los Angeles Times along with several demonstrators reported that officers first fired tear gas after protesters tried to move police barricades as the president finished speaking.

One protester told the New York Times, “The handling by the police of this peaceful protest was reprehensible. I was gassed tonight for exercising my right to express my views.”

Tensions also rose between anti-Trump and pro-Trump demonstrators toward the end of the rallies. The Times reported that the driver of a pickup truck performed the Nazi salute in the direction of the protesters, prompting them to approach the vehicle before the driver started to speed away. At least one Trump supporter also demanded to see a Latino demonstrator’s “papers.”

Police helicopters circled downtown Phoenix, ordering protesters to leave the area for about 45 minutes before the demonstrators dispersed.

According to the local news website AZCentral, “it was a chaotic ending to hours of protests that had generated tension but little violence.”

Cecillia Wang, deputy legal director of the American Civil Liberties Union (ACLU), urged protesters to contact the group if they felt their rights had been violated by the Phoenix police, and summed up the evening’s events on Twitter.