Thirty-one people were arrested at the Occupy site in Washington, DC during a nine-hour standoff over the weekend, after protesters refused to dismantle a wooden structure they had erected. Police also arrested several other protesters in Nashville, Tennessee and Portland, Oregon.

It was the first case of mass arrests at McPherson Square, in Washington, DC, according to the Associated Press.

Up until now, Occupy DC had enjoyed good relations with authorities, with only a few arrests linked to the protests and none in the Square.

The encampment, a few blocks from the White House, is one of a diminishing few in high profile cities remaining since the movement began on 17 September. There have been evictions or attempted evictions at sites across the country, including some of the largest occupations, in New York, Los Angeles and Philadelphia.

The standoff at Occupy DC happened on Sunday after protesters were told they did not have a permit for the wooden structure they had built the night before and were given an hour to take it down.

Police issued three warnings, according to the Washington Post, ordering the protesters to leave or face arrest.

A few scuffles broke out after officers moved in while protesters remained sitting on top of the structure, built as a place they could hold general assembly and keep warm for the winter, and refused to move.

Fifteen of the 31 people detained by police were arrested for crossing the police line, according to CNN. The other 15 were charged with disobeying a lawful order after police ordered them to vacate the structure. The last protester removed from the building was charged with resisting arrest, indecent exposure and urinating in public.

The standoff ended after two of the protesters jumped from the structure into inflatables provided by police, while those remaining were picked off by officers in a cherrypicker.

Rob Wohl, 23, a protester from Arizona who remained inside the shelter hours after police ordered them to leave, told the Post: "Our message today is that the public space in America belongs to the people".

In other Occupy developments over the weekend, 19 protesters were arrested in Portland after they erected tents in a downtown park and refused to leave. Some 300 people had attempted to gather in Shemanski Park late Saturday night and then marched through the streets, according to the Associated Press.

The Portland demonstrators, evicted from their occupation site three weeks ago, said on Sunday they will lobby the city for a location to pitch their tents. Several people held a vigil outside Portland City Hall, asking that a ban on camping in parks be lifted. On their website, the group said they planned to stay until the city changed its rules.

"This will be an ongoing nonviolent effort to maintain focus and attention to the issues of inequality that 99 percent of America face as the result of corporate greed and corruption," they said.

An unidentified man was reported dead at the Occupy Denton camp at the University of North Texas campus, reported the AP, according to a post on the university's Facebook page. It was unclear when and how the person died, and campus police were investigating, it said.

Police arrested four Occupy Nashville protesters and detained a journalist reporting at their site, according to The Tennessean.

Matthew Hamill, who hosts This Occupied Life on Radio Free Nashville, told the newspaper he was rounded up while filming the protesters, but was later released.

Meanwhile, in Philadelphia, a group of homeless people who have been camped under an overpass for a week and were under notice of eviction as of 11am Monday, are looking for somewhere to go.

Paul Klemmer, a homeless carpenter, has written about the plight of a group of around 20 fellow homeless who left Occupy Philly at Dilworth Plaza after the eviction to seek safe accomodation. They have been camped below an I-95 overpass but have been told by Pennyslyvania's Department of Transportation they have to leave, which they plan to do, according to Philadelphia's Citypaper.

In a letter published by the newspaper, Klemmer has detailed the dilemma for the homeless who have joined the Occupy movement.

He writes: "We've come a long way in a short time and formed the core of such a community of shared involvement and responsibility. We've been conditioned by being forced to exist alone, to grab all we can before someone else does, this alientation suiting the purposes of the status quo which would keep us invisible and blame us for our own misfortunes."

"It's been suggested that the churches of the Interfaith community might provide temporary sanctuary for our small ten community, providing a launching pad for other, longer-term solutions such as acquiring abandoned indoor or outdoor space through legal channels, disappearing into safety spaces or bouncing from church yard to church yard, doing clean up and repairs in the community, inviting community involvement and integrating the homeless with the communities. But by tomorrow, Monday, we need a place to regroup or just crawl back under the rocks we crawled out from, disappointed that the hot air generated by Occupy was insufficient to keep us warm through the coming snows."

The group packed up their things, put them into storage and dispersed by noon, Tricia Shore, an advocate for the group and member of the Friends Center told the newspaper.

"A few people are in sanctuary at Friends Center at 15th and Cherry, a few people are going to Washington, DC, with Occupy Philly for a couple days tomorrow as a coalition from Camp Liberty," Shore said. "A few people are scattered but we're keeping in contact if they have cell phones. So we're keeping the community together, and we're still waiting to hear from Mayor Nutter."