NEW YORK (CNN) — In the first major show of strength since police evicted “Occupy Wall Street” demonstrators encamped at Zuccotti Park, protesters on Thursday massed by the hundreds at their former home base, while others marched toward the New York Stock Exchange.

The group lifted metal barricades that ringed the financial district park in Lower Manhattan, scuffling with authorities and blocking traffic as police reported up to 75 arrests, many of them on streets near the Exchange.

Residents and employees were required to flash identification cards, as police cordoned off the surrounding area, said police spokesman Paul Browne.

By late Thursday morning, the Zuccotti Park crowd could be seen surging forward against a large police presence, as authorities struggled to contain the group. By noon, however, police had regained control of much of the area.

“I think the numbers have increased dramatically today,” said protester Jo Robin. “Particularly after the raid, our message is being broadcast all over the world.”

Early Tuesday morning, police swept into the group’s former encampment at Zuccotti Park and forcibly evicted demonstrators, a move that was ultimately upheld by a New York State Supreme Court.

Two days later, demonstrators gathered in cities nationwide in what organizers call a “mass day of action” to mark two months since the movement began.

A heavy police presence was in place in Los Angeles, Dallas, and Portland, Oregon, while protesters in New York kicked off the effort by marching in the city’s financial district in an attempt to disrupt trading at the Stock Exchange.

CNN personnel could see about a dozen people arrested, including a retired Philadelphia police captain, Ray Lewis, who had joined with the Occupy Wall Street protesters. He was arrested as he stood in the middle of a street near Wall Street Thursday morning.

On its Twitter Feed, Occupy Wall Street reported the arrest and added the hashtag “#shame.”

CNN iReporter Alvaro Perez shot video in Lower Manhattan showing protesters being dragged away by police, including one woman who appeared to be dragged by her jacket and backpack.

“I don’t want to speculate on what happened in advance of that,” said police spokesman Browne of the incident.

He added that the “big picture” of how police have handled demonstrations has been largely positive.

“People were able to get to work” and “protesters were able to protest,” Browne said.

Demonstrators, meanwhile, say they plan to gather at several subway stations in the city, then head north of Zuccotti Park to Foley Square at around 5 p.m., before marching over the Brooklyn Bridge.

Last month, police arrested more than 700 demonstrators as they tried to cross the bridge.

Authorities, meanwhile, say at least four police officers were rushed by ambulance to a nearby hospital after an unidentified liquid was thrown at them.

Earlier, on CNN’s “American Morning,” Howard Wolfson, a New York City deputy mayor, vowed, “We’ll make sure, if people want to peacefully protest, they have the right to.” But, he added, “if people break the law, we’ll have to deal with that.”

“If they attempt to enter a building they’re not allowed in, that’s breaking the law. If they want to express their concerns about Wall Street, that’s totally fine,” Wolfson said.

Occupy Wall Street, on its website, accused police of brutality in at least one location Thursday morning.

Browne said the city’s police department has a mechanism for reviewing cases of alleged police misconduct, but added that he did not want to comment on the allegations without a review of the facts.

On Twitter, Occupy Wall Street wrote, “Some bankers are holding signs that say, ‘get a job.’ Unemployment is at 10% and they’re smug in suits.”

Laying out the thinking behind Thursday’s plan, the group wrote, “Enough of this economy that exploits and divides us. It’s time we put an end to Wall Street’s reign of terror and begin building an economy that works for all.”

Across the country, cities braced for angry demonstrations from similar movements.

A website listing events being organized nationwide, occupytogether.org, called for “mass non-violent direct action” Thursday.

Among the events listed is “occupy colleges,” when students will gather at their school to protest rising costs and “diminishing quality.”

In Portland, plans include “occupy banks.” “Let’s shut them down!” the organizing website n17pdx.org says.

Large groups of demonstrators gathered in front of the city’s downtown hotels, carrying placards and chanting, “We are the 99%.”

In Dallas, CNN affiliate WFAA broadcast images of police sweeping through city squares where protesters had been gathering and camping.

And in Los Angeles, organizers called for a protest downtown, shutting down an intersection.

Large groups of protesters were seen flooding city streets in an apparent standoff with authorities.

Events are also planned in Boston, Minneapolis, and other cities.

While organizers stress that the plans are nonviolent, the “mass day” comes after a demonstrator in New York was arrested for allegedly making violent threats.

Nkrumah Tinsley, 29, also was accused of “aggravated harassment” on Wednesday evening in Zuccotti Park, where the movement began, New York police said.

Tinsley is seen in a YouTube video making threats toward a department store. “In a few days, you’re going to see what a Molotov cocktail can do to Macy’s,” he said.

In another part of the video, Tinsley threatens to burn New York City to the ground on Thursday.

Wednesday’s arrest is Tinsley’s second in as many months. He was arrested on October 26 for assaulting a police officer.

About 200 Occupy Wall Street demonstrators were arrested Wednesday, police said.

While the city has come under fire from protesters and other critics for arrests and removing protesters from Zuccotti Park, Wolfson insisted that “we had to act” to stop illegal activity, such as drug use, and to eliminate fire hazards.

“This is a place where we honor the First Amendment,” Wolfson said Thursday.Portland,

— CNN’s Josh Levs, Mary Snow, and Brian Vitagliano contributed to this report.