[UPDATE: VIDEO BELOW] Councilmember Jumaane Williams took a baton to the chest late last night while observing the NYPD make arrests in Zuccotti Park, where Occupy Wall Street protesters had gathered to celebrate the movement's one-year anniversary. Williams—who's tangled with police before (most notably during last year's West Indian Day Parade, when he was briefly arrested)—was shoved several times and hit with a police baton.

Officers had moved into the park shortly before midnight to make an arrest, and Williams was standing on a bench observing when a group of protesters and police spilled over in his direction. Two hour earlier, approximately two dozen riot police and a dozen white shirt officers had marched through the park in a nearly-wordless show of force—their only order was for protesters to stop standing on the benches. But this order was issued before Williams's arrival, and it's doubtful he knew about it. (He arrived at 11:45 p.m.)

Williams was not injured, and told us, "I’m okay. I told them I was a Councilmember observing. Guess they didn’t hear me." Another witness said, "I saw it from inches away. Cop hit him on legs & then other cops shoved him." Here's video of the scene—the incident with Williams starts around the 2:40 mark:

In a statement, Williams's spokesperson said:

Council Member Williams was in Zuccotti Park to observe and ensure that the rights of protesters are being protected, something which he has done at multiple Occupy Wall Street actions without incident. In the midst of a police action involving one protester, two NYPD officers approached the Council Member and pushed him while he tried to explain his purpose at the park. He was neither arrested nor injured during the incident. Council Member Williams will continue to work with the NYPD and protesters to ensure both the protection of First Amendment rights and the safety and security of our city.

There's also this:

The atmosphere at the park throughout the evening was peaceful, even if the tension between protesters and watchful police was palpable. The drummers held to an agreement to desist at 10 p.m., and birthday cake was passed through the crowd, which numbered almost 1,000 until the riot police marched through the park just after 10. That tactic had the effect of sending about half the Occupiers fleeing the park—many of them had large back packs, and although Brookfield security had allowed them to enter earlier in the evening, they were no longer permitted back inside with their gear. Some of them withdrew to the sidewalk on Broadway outside Trinity Church.

We asked one security guard how they determined what size bag was too big, and were told, "Anything that can fit any kind of sleeping gear." One young man who refused to give his name was observed in the park arguing with a security guard about his backpack. The dispute ended when the security guard told him, "You can either leave or I gotta get a cop in here to take you out." The protester then departed, shouting expletives at the Brookfield security as he left.

Here's video of the NYPD's march through the park just after 10 p.m., which resulted in no arrests but prompted at least half of the protesters to call it a night:

Riot Police March Through Zuccotti Park from Gothamist on Vimeo.

Additional reporting by Christopher Robbins.