ROUGH CUT (NO REPORTER NARRATION)br br Clashes broke out yet again on Friday (March 7) in the Venezuela capital as anti-government protesters faced off with police.br br Unrest in Venezuela has left at least 20 dead and convulsed the South American OPEC nation.br br A Reuters cameraman was injured in the clashes on Friday after being hit in the hand with a tear gas canister that was fired at protesters by the police.br br A year after Hugo Chavez succumbed to cancer, his self-proclaimed "son," President Nicolas Maduro, faces the biggest challenge to his rule from an explosion of anti-government demonstrations that have led to 20 deaths since February.br br Though the protests do not appear likely to topple Maduro, neither do they seem to be going away. A hard core of students are determined to maintain street barricades and militant opposition leaders organize daily rallies around Venezuela.