The Egyptian capital Cairo was the scene of violent chaos on Friday, when tens of thousands of anti-government protesters stoned and confronted police, who fired back with rubber bullets, tear gas and water cannons. It was a major escalation in what was already the biggest challenge to authoritarian President Hosni Mubarak_s 30 year-rule. They are demanding Mubarak_s ouster and venting their rage at years of government neglect of rampant poverty, unemployment and rising food prices.