UPDATED: Oct. 11 at 7:20 p.m.

BOSTON—Boston police arrested 129 protesters affiliated with the Occupy Boston movement, including at least five Harvard students and alumni, in a swift raid on Dewey Square in the early-morning hours on Tuesday.

The arrests were the culmination of a standoff between protesters and police after a weeklong protest in downtown Boston expanded into the northern park adjacent to Dewey Square. The protesters have permission to occupy Dewey Square, but when they expanded into the northern section on Monday, Boston police decided to take action.

On Monday, a second tent city emerged in a northern part of Dewey Square, which is adjacent to South Station, and this new camp reportedly drew the attention of city officials for lacking necessary permits.

Statements by Boston Mayor Thomas M. Menino on Sunday indicated that the protests would soon be required to disband. On Monday, the Boston Police Department released a statement saying it respects the right to protest peacefully, and insisted that protesters could stay in Dewey Square but could not occupy the adjacent park. Tuesday morning’s arrests occurred in the park.

Anxieties mounted in the camp late Monday night before police officers arrived, as rumors spread across the Dewey Square occupation through word of mouth and social media that officers were on their way to force protesters to leave.

By 12:30 a.m. on Tuesday, only a small group of police officers were stationed at the scene. But by 1:00 a.m., police officers began to collect around the square and position themselves at different corners of the camp.

Despite growing apprehension, some protesters attempted to maintain the good-humored attitude that defined Dewey Square during the day. One group gathered in a circle and sang “Let It Be” by The Beatles.

Before police blocked off the roads, the protesters were occasionally encouraged by passing cars honking in support. On the outskirts of the camp, EMT ambulances arrived as the police presence quietly grew.

Kate R. Fielding, a Boston resident, expressed a desire for the protest to remain peaceful.

“My friend and I started participating last night. When we came today, we heard that police were coming to break things up,” said Fielding. “We don’t want that to happen. We just want a peaceful protest.”

At 1:40 a.m., about 100 police officers dressed in riot gear and carrying billy clubs joined the other 100 officers already on the scene, lining up in two rows at the corner of the new camp.

Boston Police Superintendent William Evans notified demonstrators with a bullhorn that those who refused to leave within two minutes would be arrested. After between five to ten minutes, officers forcibly broke through a line of protesters and began making arrests.

Jackson F. Cashion ’13, in the north park area when the police arrived, described the showdown as incredibly tense. “For a while, it wasn’t clear where the police were going to come from. It seemed like the police were emerging from all sides,” Cashion said. “I was on the edge, and I wanted to avoid getting arrested. I was scared.”

Samuel B. Novey ’11 was in Dewey Square when the police arrived. He described the police action as hostile.