Officers arrested 10 of the demonstrators after they allegedly refused to cooperate when ordered to leave the public space alongside City Hall about 2 a.m. so it could be cleared of camping gear and refuse.According to a statement from the San Diego Police Department, participants in the open-ended protest had been given "multiple orders ... to remove their personal property" from the concourse but "continued to refuse" to do so.During a late-morning briefing on the evacuation and cleanup operation, SDPD Executive Assistant Chief David Ramirez said the six-week-old downtown rally had "become a real safety hazard" due to outbreaks of violence and unsanitary conditions, including garbage that had attracted rats.Since the middle of last month, officers have arrested a felony warrant subject, a parolee-at-large and a robbery suspect at the protest site, Assistant Chief Boyd Long told news crews.Last weekend, protesters found two live shotgun rounds and two pistol cartridges there, and an officer was bitten on the finger while trying to break up a fight that broke out between two protesters, he said.While clearing the courtyard Wednesday morning, police seized drug paraphernalia, knifes and a homemade billy club, according to Long.Though the protesters were ordered to keep tents, sleeping bags and other large personal items out of the plaza during the first ouster at the plaza on Oct. 28, those trappings "crept back in" over the subsequent weeks, Ramirez said. Police officials have decided to more strictly enforce the ban on clutter in the area, he told reporters.Stressing that the city supports the right of citizens to rally "peacefully and lawfully," Ramirez said this morning's sweep was not a "raid" but rather an "enforcement action."Of those arrested, seven are men and three women ranging from 18 to 28 years old, according to SDPD Capt. Mark Jones. Nine of them were taken into custody for resisting officers, and one was detained and cited for making excessive nose with a "sound amplifying device," the captain said.During the first compliance operation targeting Occupy San Diego, 40 people were arrested at Civic Center, and 11 more at Children's Park in the Marina area.Increasing numbers of homeless people have been joining the protesters, presumably for free food and other support, according to Long, who estimated that about 85 percent of the roughly 70 protesters at the Civic Center when officers arrived Wednesday morning are known transients.At the briefing, police officials emphasized that demonstrators would be free to go back to the plaza following the cleanup, as long as they refrained from setting up camp again.By late morning, about 75 protesters had returned. One carried a sign reading, "Occupy Still," and another displayed a placard bearing the statement, "Guess Who's Back!!"The leaders of the ongoing demonstration have vowed to stay in the downtown area until their demands -- including meaningful action addressing joblessness, poverty and political corruption -- are met or at least seriously considered.San Diego officials planned to take part in a conference call Wednesday with officials of other U.S. cities to share ideas on how best to handle the "occupy" protests, which have sprung up across the nation after beginning in New York.