Update, 715pm ET: I've been following live reports on Twitter from various sources, and the situation in Times Square sounds intense. By various estimates, 15-20,000 demonstrators have occupied the Square. NYPD are out in full force, including the Counter-Terrorism unit (photo below).
At least a dozen (maybe more) officers on horseback, and buses and paddywagons ready for mass arrests. Multiple sources on the scene describe police tactics aimed at, more or less, "kettling" people into a defined zone, surrounding them with nets, officers on horseback, and police with batons.
Here's a video uploaded a while ago that shows protesters near the "Toys-R-Us" at Times Square. And here's another, that gives a sense of the crowd density a couple hours ago. And here is another, showing mounted officers entering the area filled with demonstrators.
And below, via AntDeRosa at Reuters (a good one to follow today):
Occupy Wall Street protesters shout slogans against banks and economic system while they take part in a protest at Times Square in New York October 15, 2011 REUTERS/Eduardo Munoz
There are various reports floating around on Twitter now that NYPD has been "authorized to use tear gas" against protesters. Some on the scene are tweeting that NYPD is ordering crowds: "Leave now and you won't get hurt."
The situation sounds volatile, and like a very large number of people (including families with children, and disabled persons who have limited mobility) are packed into an ever-shrinking space. I hope this does not end badly.
Peter Rothberg of The Nation tweets:
According to multiple sources, all #OWS protesters in Times Square now face arrest if they don't immediately proceed out of the area.
Update, 8pm ET: Reports of arrests beginning, from multiple sources in Times Square. Joe Pauca: "NYPD paddywagon truck just pulled up. One person has been arrested. Now two. Both placed in truck. More getting arrested. Everyone is yelling to let them go. More NYPD paddy wagons arriving on the scene... jeffrae: Some people at 46th St seem penned in. I can't see but 3 wagons have been brought in. People chanting, 'Let them go.'"
Reuters has a live video stream here. The police are ordering the crowd to step back. The crowd chants back, defiantly, "YOU STEP BACK."
Update, 8:23pm ET: NY Daily News reports that 71 (and counting) have been arrested. Similar reports from eyewitnesses on-site.
From @somebadideas, in NYC: " Arrests, definite, NY police scanner says 2 NYPD are being transported by EMS for injuries (no details)."
From @mmflint, who is on-site: "Arrests have begun. (I mean, of peaceful citizens. Still no banker or CEO in jail.) Now we're watching people being dragged away."
And from @theother99: "Situation remains v. tense. No further arrests. NYPD presence grows. 150+ uniformed officers on site, some riot police in helmets. NYPD riot police now approaching from back side on 46th St.... at least 15+ NYPD Riot Police approach from east side of 46th St. Crowd being cleared to sidewalks."
Boing Boing reader Timothy Krause says, "Here's a photo I shot at tonight's OWS rally-party in Times Square showing a protester being arrested."
Update, 9:00pm ET: Multiple reports that the police have taken down the barricades, and what looked like a very tense confrontation has dissolved. More than a hundred arrests, by some accounts. Massive crowds at the height of the action, 20,000 or more by some estimates. Sources I'm reading on Twitter who were there describe the numbers as overwhelming.