Police in riot gear have clashed with more than 1,000 protesters attempting to march on to Oakland's city hall to condemn arrests made at an "Occupy Wall Street" camp.<br /><br />Witnesses say the police used stun grenades and tear gas to disperse the crowds away from a plaza in Oakland's business district.<br /><br />Meanwhile, an Iraq war veteran is in a critical condition as he was hit on the head with a projectile fired by the police.<br /><br />Al Jazeera's Kimberly Halkett reports.
