ATLANTA (AP) — Demonstrators marched, stopped traffic and in some cases lashed out violently at police as protests erupted Friday in dozens of U.S. cities following the killing of George Floyd after a white officer pressed a knee into his neck while taking him into custody in Minnesota. In Phoenix, Denver, Las Vegas, Los Angeles and beyond, thousands of protesters carried signs that said: “He said I can’t breathe. Justice for George.” They chanted ”“No justice, no peace” and “Say his name. George Floyd.”

After hours of peaceful protest in downtown Atlanta, some demonstrators suddenly turned violent, smashing police cars, setting one on fire, spray-painting the iconic logo sign at CNN headquarters, and breaking into a restaurant. The crowd pelted officers with bottles, chanting “Quit your jobs.” People watched the scene from rooftops, some laughing as skirmishes broke out. Demonstrators ignored police demands to disperse. Some protesters moved to the city’s major interstate thoroughfare to try to block traffic.

Mayor Keisha Lance Bottoms passionately addressed the protesters at a news conference: “This is not a protest. This is not in the spirit of Martin Luther King Jr.”

“You are disgracing our city,” she told protesters. “You are disgracing the life of George Floyd and every other person who has been killed in this country. We are better than this. We are better than this as a city. We are better than this as a country. Go home, go home.”

Bottoms was flanked by rappers T.I. and Killer Mike, as well as the King’s daughter, Bernice King.

Killer Mike cried as he spoke.

“We have to be better than this moment. We have to be better than burning down our own homes. Because if we lose Atlanta what have we got?” he said.

After Bottoms appealed for calm, the violence continued. More cars were set on fire, a Starbucks was smashed up, the windows of the College Football Hall of Fame were broken, and the iconic Omni Hotel was vandalized.

In Brooklyn, crowds of demonstrators chanted at police officers lined up outside the Barclays Center. There were several moments of struggle, as some in the crowd pushed against metal barricades and police pushed back.

Scores of water bottles flew from the crowd toward the officers, and in return police sprayed an eye-irritating chemical at the group twice.

The names of black people killed by police, including Floyd and Eric Garner, who died on Staten Island in 2014, were on signs carried by those in the crowd, and in their chants.

“It’s my duty to be out here,” said Brianna Petrisko, among those at Foley Square in lower Manhattan, where most were wearing masks amid the coronavirus pandemic. “Our country has a sickness. We have to be out here. This is the only way we’re going to be heard.”

In Houston, where George Floyd grew up, several thousand people rallied in front of City Hall. Police had apparently taken into custody a woman who had a rifle and had tried to use it to incite the crowd.

Jimmy Ohaz, 19, came from the nearby city of Richmond, Texas.

“My question is how many more, how many more? I just want to live in a future where we all live in harmony and we’re not oppressed.”