Officers say they were threatened by a man with a firearm.
The injured man is under arrest and in a stable condition in hospital.
We have referred the matter to the IPCC and will support them in their investigations."
More top news
We've been getting acquainted with the Shaun the Sheep sculptures heading out on location for this summer's trail across Bristol
The Shaun in the City sculpture trail, which hits Bristol's streets on Monday, was given its official, and typically unusual, launch today.
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