Tensions between Occupiers and police intensified over the weekend in Portland, Oakland, Denver, and other U.S. cities as municipalities stepped up their efforts to remove the protesters from city property.

In several of the incidents, officers were assaulted by protesters.

In San Francisco, two officers were attacked in separate incidents at The Embarcadero and Broadway where San Francisco Police were attempting to hold the line against protesters. In the first incident, a female attacked an officer with an razor blade attached to a pencil-like object. In the second attack, a male demonstrator grabbed an officer's radio from his duty belt. The officer's uniform was torn, and he suffered an injury to his cheek while attempting to retrieve the radio, reports the San Francisco Examiner.

In Denver, three Occupy protesters were arrested Sunday after scuffling with police. A Denver Police officer and Colorado state trooper were injured during a shoving match when the officers attempted to move a table being used to serve food, reports the Denver Post.

Oakland again showed its combustible potential, as Oakland Police again cleared the tent city outside of City Hall. Hundreds of officers converged before dawn on the encampment at 14th Street and Broadway to arrest 32 Occupiers, reports the San Francisco Chronicle.

Over the weekend, an activist with Berkeley CopWatch posted a video showing Oakland Police Officer Fred Shavies and another officer attending Occupy protests in plainclothes. The video, which went viral, included a soundtrack with audio from 2003 of acting chief Howard Jordan telling the police board of review that the agency infiltrated an anti-war group at that time.

To respond to claims that he was infiltrating the group, Officer Shavies agreed to a video interview with a photographer to respond to the CopWatch video. In the interview, Officer Shavies said he sympathizes with protesters, reports the New York Times.

The weekend's high arrest count came in Portland, Ore., where 51 protesters were taken into custody. Officers decked out in riot gear didn't use tear gas or rubber bullets, reports The Oregonian.

Salt Lake City Police on Saturday cleared the Occupy SLC campsite at Pioneer Park, and Occupiers vacated the park nonviolently. Several were handcuffed, reports the Salt Lake Tribune.