Police officers watch a group of protesters sitting on the street near a temporary detention centre on Sunday. (Jacques Boissinot/Canadian Press)

By Jennifer Hollett, CBC News

Outside the city's east end Toronto Film Studios everyone plays their part. Protesters sing and chant "let them go" to live music. Media capture the moment. Police stand on guard.

Protesters organized at 10 a.m. this morning at Jimmie Simpson park. After assuring police, media and other protesters they'd protest peacefully, they marched east to the temporary detention centre where their "comrades" are.

The protest is indeed peaceful, and even playful.

Scratch that.

As I was writing that the protest took a turn. Police stormed the crowd with batons and arrested one woman. Activists are now sitting down singing "We are peaceful, how about you?"

Peace signs are in the air as police watch on.