Despite state-organised rallies in support of Muammar Gaddaffi, thousands of pro-democracy protesters defy a security crackdown to demand an end to his 42-year rule.br br Videos posted online claim to show demonstrators setting fire to the police headquarters in the eastern city of Benghazi. br br Al Jazeera speaks to an eyewitness who describes seeing protesters shot dead by Gaddaffi loyalists.