Occupy Crackdown: Beginning of the End for Protests? Violence in several cities sparks leaders to call for end to the camps.

OAKLAND, Calif., Nov. 13, 2011 -- The tension is mounting outside Oakland's City Hall after police issued three eviction notices to anti-Wall Street protesters over the weekend, telling demonstrators they do not have the right to camp overnight.

Still, 150 tents remained today in Frank Ogawa Plaza.

Though authorities have not said when or if they plan to raid the encampment, protesters are bracing for a crackdown when the sun goes down.

Oakland police issued similar warnings to Occupy Oakland before raiding the campsite on Oct. 25. More than 80 protesters were arrested and the clashes turned violent. Police used tear gas and bean bags, seriously injuring an Iraq war veteran in the process. He was reportedly released from the hospital, but his friends say he still has trouble speaking.

But the movement that garnered support around the country, is now facing backlash from city governments nationwide.

Police in many cities say they have run out of patience and officials are raising concerns about what they call unsanitary conditions, even a growing number of crimes at some camps.

Over the weekend in Philadelphia, police arrested a man after a woman was dragged into a tent and sexually assaulted.

"Occupy Philly has changed," Philadelphia Mayor Michael Nutter said today. "We're seeing serious health and safety issues playing out on almost a daily basis. Occupy Philly is fractured, with internal disagreement and disputes. The people of Occupy Philly have also changed. And their intentions have changed. And all of this is not good for Philadelphia."

At Occupy Albany, N.Y., police arrested dozens of campers for defying a curfew. A man committed suicide at Occupy Vermont. In Salt Lake City, police arrested 19 people for refusing to leave a park one day after a man was found dead in his tent.

The largest clashes over the weekend occurred overnight in Portland, Ore., where there was a heated faceoff between officers in riot gear and thousands of demonstrators.

Protesters built barricades with wood debris and old furniture to block streets. Most finally agreed to leave, but police pushed out a few hundred stragglers late this afternoon.

And at Occupy San Francisco, police say two demonstrators used a sharp object to attack two officers during a march.

In Oakland, Mayor Jean Quan released a statement saying, "While the camping must end, the movement continues."