CHICAGO -- Protesters took to the streets in dozens of cities nationwide Saturday to call on President Trump to release his tax returns, saying Americans deserve to know about his business ties and potential conflicts of interest.

Organizers said the protests -- dubbed the Tax March -- were scheduled in nearly 150 cities, and stemmed from the women’s march that took place the day after Mr. Trump’s inauguration.

In Berkeley, California, police arrested more than a dozen people at unrelated gatherings of pro- and anti-Trump people in a park after fist fighting erupted. Officers confiscated knives and makeshift weapons. Nearly 200 people were at Berkeley’s Martin Luther King Jr. Civic Center Park when several people began pushing each other. Dozens of police officers in riot gear stood nearby and began breaking up the confrontation.

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In Chicago, nearly 10,000 people indicated on Facebook they would attend demonstrations, CBS Chicago reports. Tuesday, April 18, is the deadline for taxpayers to file returns.

Mr. Trump, who spent the morning at his Florida golf course, avoided several hundred protesters when his motorcade took a circuitous route back to Mar-A-Lago, his Palm Beach, Florida, estate. Protesters marched across the bridge that divides West Palm Beach and Palm Beach, chanting and hoisting signs that read “Don the Con,” ‘’Go back to New York,” ‘’Show your taxes!” and “Show me the money!”

Mr. Trump is the first major party nominee in more than 40 years to not release his tax returns, saying it was because he was under audit. He later said that voters don’t care.

“We do care. We want to see his taxes,” said Ann Demerlis, who was among hundreds who marched in Philadelphia from City Hall to an area in front of historic Independence Hall, carrying signs and chanting “We want your taxes now!”

“It’s possible that he can now show his taxes, because his current taxes are not being audited,” said Demerlis, who carried a sign saying, “Follow the Money.”

Protest organizers say Americans deserve to know about Mr. Trump’s business ties and potential conflicts of interest.

Protesters in New York City gathered at Bryant Park in midtown and were scheduled to march to Trump Tower, according to CBS New York.

Comedian Sarah Silverman speaks at a march demanding President Donald Trump release his tax returns, in New York, U.S., April 15, 2017. REUTERS

The Washington, D.C., march began with a rally at the U.S. Capitol, where Sen. Ron Wyden called on Trump to ‘knock off the secrecy.” The Oregon Democrat says the people have “a basic right to know whether the president pays his fair share.”

“We’re marching on Washington, D.C., and around the country to ask Donald Trump: WHAT ARE YOU HIDING?” the organizers’ website says. “We need a president who works for all Americans, and a tax system that does, too. Release your tax returns and commit to a fair tax system for the American people.

For four decades, presidents and major party nominees have released some of their tax returns, with the exception of Gerald Ford. Trump’s break with precedent has raised questions about possible conflicts of interest.

Jennifer Taub, an organizer who kickstarted the movement, told CBS News ahead of the event that she wasn’t sure what to expect.

“I’m just a law professor who sent out a tweet,” said Taub, who teaches at Vermont Law School. “I’m psyched, and I think lots of people are psyched about this. We shall see.”

Taub’s tweet about planning a protest stemmed from her general interest in financial matters. She has testified before Congress and wrote a book about the 2008 financial crisis.

“I’m all about ‘follow the money,’” Taub said. “It tells us the story about people’s priorities.”

Democratic U.S. Sen. Elizabeth Warren, of Massachusetts, on Friday posted an online video urging Congress to force Trump to release the returns. “Donald Trump is hiding something,” she says. “And we know where he’s hiding it: not in a safe, not in a vault. Nope, he’s hiding it in his taxes.”

Democrats are pushing for a vote on a bill from Rep. Anna Eshoo, a Democrat from California, which would require the president and all major-party nominees to publicly disclose their previous three years of tax returns with the Office of Government Ethics or the Federal Election Commission.

Republicans also have rebuffed Democrats’ efforts to get the House Ways and Means Committee to act. It has legal authority to obtain confidential tax records, and could vote to make them public.