David Nicholls has told ITV Central that "it will take a while to recover" after he was attacked with a sledgehammer while at work.
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A gunman who held two members of staff hostage at a bowling alley in Nuneaton has been arrested.
There are reports of flash-bangs being used at Bermuda Park as ambulances arrive at the scene.
Chris Turner, an eyewitness to the incident at Bermuda Park, said a man was carrying a shotgun and told him to "get out of the way".