Notre Dame: Blaze engulfs medieval icon

It is one of the most famous buildings in the world. It has stood on the banks of the river Seine for more than 800 years. Tonight Notre Dame Cathedral in Paris is completely engulfed by fire. Huge crowds gathered in the streets around it - many were in tears. Notre Dame took 200 years to build - it's one of the greatest treasures of medieval architecture. Tonight it lies in ruins.