NEW YORK—Throngs of pillow-armed citizens converged on Union Square near 14th Street on Saturday to hold one of the many events for the International Pillow Fight Day.

"I got a few swings in," said one pillow fighter walking from the crowd, breathing heavily, with feathers clinging to his sweat-covered face.

A pillow fighter dressed as Transformer's Optimus Prime was singled out in the crowd.

"Get Optimus Prime!" shouted one person in between swings.

Meanwhile, outside the massive circle of people, people laughed and looked on in disbelief. Over the crowd of people, one could barely see the faces of those engaged in the fight, but could only see swinging pillows.

"This is crazy," said one young lady, looking onward with a look of incredulity on her face.

"Creepy," said another.

Indeed, the massive swarm of people slugging each other was a little disorienting. The cluster of people was so dense that the pillow fighters had difficulty even swinging their weapons. Therefore, some fighters chose to just catapult their weapon above the crowd.

But all-in-all, Americans have the First Amendment right to assemble—even if just to swing pillows for several hours.

The unofficial organizer of the event, Newmindspace, said that approximately 150 cities take part in the action. As a rough estimate, most of the people who partook in the event in New York City were between the ages of 15 and 25, although there were some small children and older residents involved.

Police officers were on standby and had several walkways throughout Union Square blocked off.

“You have to go to the East side of 14th Street!â€