(CNN) -- Occupy activists and law enforcement authorities found themselves at odds in several U.S. cities over the weekend, including yet another tense showdown late Sunday afternoon in Portland, Oregon.





Police in riot gear and holding batons lined up for hours along a city street, face-to-face with activists who refused to clear the road and go onto the sidewalk. This confrontation came hours after Portland police Sgt. Pete Simpson said more than a dozen people were arrested as authorities cleared Chapman Square, the last city park where protesters had gathered.





Simpson said the officers were in riot gear as a precaution, and were joined by other assisting agencies. "We needed the manpower because we used up a lot of resources yesterday (Saturday)," he said.





Mayor Sam Adams said late Sunday afternoon that "a series of increased drug overdoses... an arsonist that used the camp as camouflage and almost a 20% increase in crime surrounding the encampment" prompted the move.





"All of us are working really hard at keeping the peace and protecting freedom of expression," Adams told CNN. "I support a lot of what the encampment stands for ... (But) it shouldn't be focused on port-a-potties and tents and encampments attracting criminal elements. I think this movement needs to evolve."





Kari Koch, one of the activists, told CNN that she was "extremely disappointed that the mayor chose to crack down on these parks when the outpouring of support (among area residents) has been so strong."





"Homeless people exist, drug addicts exist, mentally ill people exist. We were a safe place they could go, and that created some problems," she said. "And we were working to deal with those problems, and the mayor cut us off."





Video from earlier showed authorities dismantling tents at the camp. Once the parks -- which Simpson said are "pretty beat up" -- are cleared, temporary fencing will be erected so repairs can be made.





One officer was struck in the leg earlier Sunday by a projectile thrown from a crowd, and was taken to a hospital, but the injuries were not life-threatening, authorities said. One protester was arrested in a separate incident overnight, Simpson said.





Video from that scene showed masses of protesters -- about 7,000, according to Koch -- on downtown streets. In the early-morning hours Sunday, police told demonstrators to leave the streets or face arrest. All but two of the demonstrators followed that order, many retreating to several parks, CNN affiliate KGW reported.





Yet hundreds returned by early Sunday morning -- some of whom have not been affiliated with the Occupy movement until now -- apparently hoping to witness a police confrontation, police Lt. Robert King said.





On Sunday, Mayor Sam Adams praised police for showing professionalism and restraint, noting the lack of serious injuries incurred over several police actions and stressing a calm, well-communicated approach.





"I'm prioritizing patience," he said earlier in the day. "In order for us to do this peacefully, we need the time and folks on the ground need the time to do their work right."





In Denver, meanwhile, two police officers were injured and two Occupy activists were arrested late Sunday afternoon, according to a statement from that Colorado city's police department.





Protesters became upset when police began removing a food table from a park, some of them surrounding a police car. One woman then pushed a Denver police officer, according to the police statement. She and a male who came to her aid were arrested.





One officer twisted his knee, while another was treated and released from an area hospital after being hit in the head, police said.





This scuffle took place after, on Saturday night, police in riot gear arrested 17 people as they cleared furniture and tents from an Occupy encampment near the city's civic center, police spokesman Sonny Jackson told CNN. The main issue, he said, was that the items were blocking a right of way.





"People are welcome to come back and
How many police were injured? Where were the riot police? What did the SLC police do? How many activists were arrested on Sunday? where is occupy camp
two Portland arrested 17 people more than a dozen Portland, Oregon.
question: How many police were injured?, answer: two | question: Where were the riot police?, answer: Portland | question: What did the SLC police do?, answer: arrested 17 people | question: How many activists were arrested on Sunday?, answer: more than a dozen | question: where is occupy camp, answer: Portland, Oregon.