Chapel Hill, N.C. — Chapel Hill police defended the force used in arrests at an illegal encampment inside an unoccupied building downtown Monday during a town council meeting, saying riot gear and assault rifles were necessary to raid the building.

"We did not know what we were walking into," said Police Chief Chris Blue.

Supporters of those arrested, however, heckled local officials over the police response to the incident.

Police said more than 70 attendees from an anarchist book fair broke into the former Yates Motor Co. building, at 419 W. Franklin St., on Saturday. Police monitored the group until the crowd reached a more manageable size, and then a tactical team moved in late Sunday and arrested seven people.

Ellen Crawford, 23, of Richmond, Va., Eva Jones, 22, of Chapel Hill, Daniel Regenscheit, 27, of Chapel Hill, Kassandra Ofray, 21, of Pittsboro, David Maliken, 24, of Carrboro, Monica Ganguly, 29, of Chapel Hill, and Jack Jarrell, 24, of Carrboro, were each charged with misdemeanor breaking and entering.

"We did not break in. The building was already open," supporter Amanda Ashley said Monday.

Blue couldn't even get a word out at a Monday afternoon news conference before supporters of the group started booing him and shouting accusations of excessive force by officers.

Photos and videos taken by people during Sunday's arrests showed police in riot gear pointing assault rifles at the protesters and pinning some to the ground.

Chapel Hill Mayor Mark Kleinschmidt's statement that police responded "in a deliberate and measured way" brought laughter from people attending the news conference.

As the crowd at the news conference got ugly, Kleinschmidt asked for respect.

"You can leave if you're going to continue to disrupt this," he told one man.

An unidentified man in the audience shouted, "You put a gun in someone's face, that is not respect. It's our Town Hall. It's our forum."

Blue said that officers tried to confront the crowd inside the Yates Motor building on Saturday but found some wearing masks and hoods and acting in a threatening manner. 

"This was a reaction we had not encountered in any of our interactions with the 'Occupy Chapel Hill' group," he said. 

The "Occupy" group has been protesting peacefully for weeks outside the Chapel Hill Post Office. Supporters said the seven who were arrested Sunday were part of the group that has been at the post office.

"I do believe it was appropriate," Blue said of sending the tactical squad in on Sunday. "I will tell you we review every use of force – and we will review our use of force – but we believe our response (Sunday) was the appropriate measured response to a set of unknown risks."

Police said the group inside the Yates Motor building had obscured windows with large banners, and some members were posted on the roof as lookouts. Anarchists use such strategies to take over buildings and destroy property, police said.

Inside the building, police said, they found flammable material, a bag of rocks and pamphlets that discussed the number of people needed to overturn a police car.

The Yates Motor building has been vacant for several years, and Ashley and others said the protesters only wanted to "recycle" it for a useful purpose – a community center and a base for local outreach programs.

"The building has been unused, neglected and thrown away by the owner," she said. "Many, many, many people have been in that building. That building has been unattended and thrown away like a discarded soda bottle."