A large number of police gather to remove an Occupy Cal encampment that sprung up on Sproul Plaza on the campus of UC Berkeley this afternoon.

On Monday UC Berkeley Chancellor Robert Birgeneau sent out a stern campus-wide letter warning against setting up tents or disturbing classes, saying:

Any activities such as pulling fire alarms, occupying buildings, setting up encampments, graffiti, or other destructive actions that disrupt with anyone's ability to conduct regular activities -- go to class, study, carry out their research, etc. -- will not be tolerated.

NBC Bay Area has the chopper cam from earlier today: