A crackdown on the Occupy DC encampment in downtown Washington ended with 31 arrests on Sunday following a nine-hour standoff with District police.

The demonstration in downtown Washington DC has been spared from police crackdowns since it began, setting it apart from sites in New York, Los Angeles and other major cities where cops have closed down spaces to protesters as the Occupy movement swells in size. Law enforcement arrived early on Sunday in DC’s McPherson Square, however, and ordered protesters to dissemble a wooden structure that was erected overnight in their encampment. The consensus among demonstrators was to keep the building, a wooden barn-like framework, intact, and police responded by arresting more than two dozen protesters early in the day.

The Washington Post reports that 15 demonstrators were arrested and charged with crossing a police line, with another 16 apprehended for disobeying a lawful police order.

After apprehending the two dozen-plus, however, protesters refused to dismantle the structure, which was built with the intention of creating a house for teach-ins and future General Assembly meetings.

Pentagonal in shape, one of the architects told the Washington City Paper that the structure was created in an effort to “reclaim the geometry,” referring to the headquarters of the US Department of Defense in nearby Arlington, Virginia.

As police barricaded off the scene and cops swarmed the park, several demonstrators climbed the framework of the unit and stayed for hours while law enforcement tried to determine a way to issue arrests on the people that were sitting roughly 20 feet in the air. Police inflated a balloon-like device and encouraged two protesters to voluntarily vacate the building and jump onto the prop for safety, but officers resorted to engaging a cherrypicker to get access to the top of the building to apprehend the others. By 7 p.m., only one protester, identified as an occupier named David, remained and refused to loosen his grip on the structure while no fewer than four cops wrestled with him from above and tried to bring him into custody.

Although the Washington Post reports that no injuries were reported, tweets and other reports on the scene suggested that cops struck David repeatedly with a police baton and appeared to be choking him at the height of the standoff.

Police action in McPherson has been peaceful since the demonstrations began earlier this year, especially in comparison to other large metropolitan cities such as Boston and New York, where crackdowns have gone violent. The DC police have allowed protesters to camp indefinitely with tents, but said that the construction of what appeared to be a permanent-structure would be prohibited since the group did not have a permit.

Police were able to dismantle the “permanent structure” with ease shortly after the standoff ended.