A fire has ripped through a 10-story building in Sydney's CBD this morning, forcing police to set up a 200 metre exclusion zone around the building due to fears of a gas explosion.

According to a New South Wales Fire and Rescue spokesperson, the blaze was caused by a sheet of scaffolding catching alight and collapsing, resulting in smoke and fire engulfing the building.

Everyone in the building had been evacuated, with seven fire fighting teams being dispatched to combat the fire.