From the San Francisco Chronicle via RSN
Oakland police have begun arresting protesters at the sprawling Occupy Oakland encampment outside City Hall while hundreds of law-enforcement officers square off against protesters downtown in the second such raid of the tent city.

Law-enforcement officers from numerous Bay Area agencies began arriving in force at 5 a.m. as a police helicopter flew overhead. Clad in armor and riot helmets, they stood in lines and surrounded the camp near the corner of 14th Street and Broadway adjacent to Frank Ogawa Plaza, where dozens of demonstrators have been camping to protest economic inequity and corporate greed.
About 6 a.m., police began arresting protesters at an “interfaith tent” on the plaza, 40 minutes after police issued an order to disperse. They sang “We Shall Overcome” as they were handcuffed. Other officers have begun clearing out tents on the plaza and have set up metal barricades at the corner.
The bulk of the protesters were outside the camp, milling about at 14th and Broadway, where some danced a few feet from police while others marched in a circle. A number of protesters are wearing bandanas, gas masks and goggles.
Shon Kae, 30, of San Francisco said protesters have separated themselves into two group, one to defend the tent city, the other to protest as police move in.
Although the camp has dwindled in recent days from about 150 tents to 60 or 70, some protesters have defied repeated orders by Oakland police to leave.