A protest around Donald Trump’s Minneapolis campaign rally escalated Thursday night from peaceful chants and sign-waving to an impasse with police on the rainy downtown streets.

As the president finished his event at Target Center, some outside began blocking cars of attendees trying to leave, calling the drivers racists and throwing plastic bottles and traffic cones at their vehicles. A group burned a pile of the president’s merchandise, including the signature red “Make America Great Again” hats. Trump supporters flipped them the middle finger as they sped by. Minneapolis police arrested one person as of 11 p.m. Thursday, according to a Hennepin County Sheriff’s Office spokesman.

Though most in the protests remained peaceful, the disrupters prompted police on horseback and bicycles to form protective lines around the agitated crowd, spraying some with chemical irritant. Many in the crowd stood their ground, shouting “Whose streets? Our streets!” as the police blocked off major downtown roads.

Trump’s event drew thousands to the heart of Minneapolis on Thursday evening, from die-hard fans trying to catch a glimpse of the president to opponents calling for his prompt removal from office. Early in the night, the groups were split into two areas of downtown to prevent clashes before the event, a chain-link fence cordoning off several downtown blocks. Trump protesters spanning many generations filled the streets, some chanting “Lock him up!” and “No Trump, no KKK, no fascist USA!” Early in the night, a few skirmishes broke out between protesters and Trump supporters, and police detained a few members of the pro-Trump group the Oath Keepers after they were reported to be carrying guns at their hotel, but they were searched and released.

Sara Witta, 50, of Edina, who runs a small graphic design company, was there with her husband, Jay, and her mother, 75-year-old Bonnie Safe, as the three prepared to enter Target Center to support Trump.

“There’s a swamp and it needs to be drained,” she said. “He’s disrupting what’s going on, the status quo, and they will do everything to get him out of the way.”

The three quickly became a target of protesters as they walked through the crowd.

“Shame on you!” the protesters screamed, many of them blowing whistles. “How does it feel to be a racist and a bigot?” another asked.

Afterward, Sara Witta said: “I think that was the worst of society imaginable.”

Bee Yang, 31, of Brooklyn Park, a Honeywell technician, said he was protesting because Trump was “running America down the drain.”

Sentiments about Trump were even evident miles from downtown, including at an overpass on Interstate 394 in St. Louis Park, where two people stood on each side of an “IMPEACH” sign and waved to the motorists below.

As the event ended, Trump supporters made their way through the phalanx of protesters in small groups.

“Nazi scum! Off our streets!” the protesters shouted.

A Hispanic couple wearing Trump gear, along with what appeared to be their teenage daughter, made their way down First Avenue while protesters yelled.

“He hates you,” the protester said to the family, referring to Trump. The woman retorted: “Mexicanos por Trump!”

A few protesters threw plastic bottles and cups at police; others called on the crowd to remain peaceful.

“This is about showing the world that a whole bunch of people showed up to protest Trump,” said Zach Fagerness, a 26-year-old Minneapolis software engineer. “A couple people yelling doesn’t matter, but when you have an army of people screaming, that’s what matters.”

“If only this many people would show up to vote,” quipped his sister, Sarah Fagerness, a 22-year-old Minneapolis nurse.

Staff writers Chao Xiong, Maya Rao, Rochelle Olson, Libor Jany and Matt DeLong contributed to this report.