About 100 Occupy Wall Street demonstrators gathered in the main concourse at Grand Central Tuesday night to protest the National Defense Authorization Act. 3 were arrested, according to the MTA, and 2 were issued summonses.

"There's an amendment in there that basically makes our country a place where any citizen can be detained indefinitely without a trial and without due process," Brendan Burke, an organizer, told The New York Times of the NDAA.

Obama's signature on the Act also included a signing statement which offered reservations regarding the indefinite detainment of US citizens.

Some protesters placed black bags over their heads, imitating images from Abu Grahib. "It's in reference to the detention that people face today," one protester told the Daily News, "what our citizens are facing today."

The "Day Of Action" began around noon at the New York Public Library, where participants gathered before marching on the homes of Senators Kristen Gillibrand and Chuck Schumer.

Then around 5PM during the afternoon rush, they marched into Grand Central.:

One member of the protest says a woman was arrested merely for starting the People's Microphone-- that call-and-response technique that has been a feature of the protests from day one. "I heard the NYPD say 'if she does it one more time [mic checks] go get her.' Arrest happened seconds later. No warning, " Jeff Smith tweeted last night. The MTA says the 3 people were arrested for disorderly conduct.

Afterwards, protesters held a meeting at 100 William Street.

A video of an arrest:

And another: