Police at the scene confirmed that someone had been subdued with a Taser and arrested, but they gave no further details.
The encounter occurred as Park Police passed out fliers warning of the deadline to begin enforcing a long-standing ban on camping overnight in the square. A protester known as Lash became angry when police entered his tent, demonstrators said.
“He told them: ‘Get out of here, get out of my tent. You’ve already given us enough of these,’ ” said Tracy Keith, 49, a researcher from Raleigh, N.C., who has been in the square for months. Keith said the protester ripped the flier and followed the police around the encampment, tearing down other fliers as the confrontation escalated.
Ellie Milne, 23, of the District said she thought three officers used excessive force by shocking Lash after he was in handcuffs.
“My mother is a police officer, and I grew up trusting the police, but this was blatant police brutality,” Milne said.
A video of the incident, which a protester posted on YouTube, appears to show that the man was not handcuffed when police used the device.
Milne, who works as a nanny, said the officers then dragged him out of the park as he pleaded for an ambulance. Other protesters became angry when police instead put him in a police vehicle.
But the driver of a passing sport-utility vehicle shouted praise to police officers who were in a tense standoff with a group of demonstrators after the arrest.
Robert Fields, who visited the square Sunday, said it was time for the occupiers to go and criticized authorities for allowing the tents to remain so long.
“This is camping, I’m sorry,” Fields, 56, of Manassas, said.
The protester arrested Sunday was not immediately identified by police. Sgt. David Schlosser, a Park Police spokesman, said that the protester was taken to a hospital but declined treatment and that he would be held on a charge of resisting arrest. The agency has opened a routine inquiry into the use of force by police.
In a written statement, Del. Eleanor Holmes Norton (D-D.C.) urged demonstrators to show authorities “the same respect and civility that [the National Park Service] and the District of Columbia have shown to Occupy D.C.”
But some protesters said Sunday’s arrest created a confrontational mood ahead of Monday’s deadline. At the base of Maj. Gen. James B. McPherson’s statue, demonstrators met to discuss their next move. Some tried to evict a reporter as the discussion turned to whether protesters should submit to arrest en masse if police began removing tents and what the main message of their protest should be.
“A lot of media attention of the movement has focused on confrontation. But the real reason we’re here is, we have a deep hope — and this may sound like a cliche — that another world is possible,” said Kathleen G. Sutcliffe, 32, a former journalist who works for a nonprofit group. “It’s not about scuffling.”
Watch the Occupy D.C. live camera from McPherson Square.
Photos: Faces of the Occupy DC movement