Updated

Demonstrations in New York City continued with nightfall, as thousands of "Occupy" protesters massed at a downtown plaza and then peacefully marched across the Brooklyn Bridge -- aiming for a grand finale to a long day of activism that led to more than a hundred arrests and injuries to at least two police officers.

With some 11 hours of marching already in the books and under a darkening, cloud-covered sky, the indefatigable horde caught its breath at Foley Square, a short distance from the bridge. They buoyantly chanted and pumped signs like delegates at a political convention, and some danced boisterously.

From there, they marched on to the Brooklyn Bridge's pedestrian walkway in lock-step with the sounds emanating from of a brass horn assemblage that had, somewhere along the way, joined the contingent. Passing automobiles crossing the bridge on the adjacent roadway honked their horns -- either in a show of solidarity with the marchers or in opposition.

But the protest's festive conclusion followed an often rancorous day of occasional violence.

Hours earlier, two New York City police officers were injured. One was slashed in the hand and a second officer was taken to a local hospital with an eye injury, after clashes with protesters and activists across lower Manhattan, sources told FoxNews.com.

More On This...

Both officers are said to be in stable condition, although the incident marked an escalation of tension in the uneasy give-and-take between New York officers charged with maintaining order and protesters determined to be heard.

The injuries were reported after a long day of marches and demonstrations across Manhattan's Financial District by protesters, driven by various grievances but generally opposing an economic system that, they say, benefits the rich while squeezing the majority of Americans. Like-minded protesters have also staged demonstrations in other cities, and clashes with police have intensified since last weekend.

In New York City, law enforcement sources said a single officer, on duty at the time, waded for unknown reasons Thursday into a mass of protesters in Zuccotti Park, the epicenter of the Occupy movement. Once there, the officer called for back-up, and two additional officers responded to the call for help and joined the original one.

Something was thrown at the eyes of the original officer, perhaps an irritant, law enforcement sources at the scene said. Then, moments later, something "sharp" was thrown at one of the officers providing back-up, causing a deep gash on this thumb, one of the sources said.

The officer hit in the eye was taken to Bellevue Hospital, where his injured eye was "flushed out," a law enforcement source said. The second officer was taken to an unidentified local hospital, where he was due to receive numerous stitches to close the gash on his hand, law enforcement sources told FoxNews.com.

The protesters took to the streets Thursday morning, marking two months since the movement's beginning, but with far less than the anticipated 10,000 activists marching on the heart of the Financial District. Only about a fifth of that number appeared to amass in lower Manhattan.

The new protest action comes two days after cops rousted the ragtag bunch from their encampment in Zuccotti Park.

Displaced but still determined, the marchers symbolically started at the now-cleared plaza as the sun rose above Manhattan and suited squads of traders and brokers arrived for regular shifts. The protesters headed for another symbolic destination -- the New York Stock Exchange. Roughly 100 arrests were reported to FoxNews.com by a law enforcement source.

New York police did their best to keep the protestors on the periphery of the plaza in front of the exchange, cordoning off the area with metal barricades, scooters and parked vans. Only a smattering of the officers wore helmeted riot gear, the rest sporting their blue, workaday attire.

But as soon as one of the many side streets leading to the Exchange in the warren-like Financial District was blocked by police, the protesters resumed their march and headed for another entry point.

Blocked from access to the plaza, the march effectively surrounded the outskirts.

"We just encircled Wall Street. We'll do it all day," said David Suker, a protester who was among the crowd, distributing copies of the "Occupy Wall St. Journal."

"If we don't have the park, we'll take the streets. If we can't take Wall Street, we'll take the side streets," he said.

The emboldened crowd carried signs and chanted slogans, like "These are our streets!" and "We are the 99 percent," as it wended its way in a circular pattern around the NYSE's plaza.

Police set up a checkpoint where NYSE employees could enter the plaza. A few hundred protesters massed there and heckled the arriving workers with chants of "Shame! Shame! Shame!" and "Shut it down!"

Some protesters blocked traffic on street in the Financial District. Police responded by peacefully herding the group back to the sidewalk.

The protesters appeared to number between 1,000 and 2,000, although they had splintered into numerous, smaller groups, making an accurate assessment difficult.

"As the day goes on, you'll see more and more people, especially when they start to gather at Foley Square," said Kanene Holder, an Occupy for Wall Street spokesperson. "Once people (get) out of work, that's when you'll see more."

Police herded handcuffed protesters into idling paddy wagons. Holder put the number of arrests at 35, yet a law enforcement source told Fox News the number is closer to 100.

One unfortunate who was headed to work on Long Island got accidentally enmeshed in a group of protesters and was arrested.

"I didn't do anything," a handcuffed Shaun Bowlin told FoxNews.com as he awaited entry into a waiting wagon. "I was walking and got caught up in the crowd. They threw me down and dragged me off. I'm not even part of the protest."

The "Occupiers" retreated with the passing of noon to familiar ground -- their old haunt at Zuccotti Park -- to regroup and plan their next move on the proverbial 1 percent.

From there, the indefatigable crowd marched uptown to Union Square, congregating in numbers that seemed to the eye to be about 2,000, near the renowned park's arch. After two or so hours, they double-backed downtown toward Foley Square in preparation for what many protesters said would be the long day's finale -- a provocative march across the iconic Brooklyn Bridge.

The day of action had been planned before the city cracked down on the encampment in Zuccotti Park, but took on added significance after tents, tarps and sleeping bags were cleared out early Tuesday and the granite plaza was cleaned for the first time since the group arrived more than two months ago.

"We will get boots on the ground again," said Rory Simpson, 29, who described himself as an itinerant activist as he made signs Wednesday evening. "This is not over yet."

Organizers say the loss of the Zuccotti Park campsite may help broaden the movement. The head of the group's finances says it will open a dialogue with organizers in other cities and take the protest to the next level.

A judge in New York ruled Tuesday that the protesters could return to Zuccotti but could not set up camp. Meanwhile, one protester was calling Thursday's action a success.

"I think this has far exceeded our expectations," Mark Bray said. "We wanted to shut down business as usual. I think we've done that. We've certainly thrown off the routine, and that is what we wanted to accomplish."

The Associated Press contributed to this report.