Yesterday was one of the busiest Saturdays of the year with 215,000 customers visiting The Bullring shopping centre in Birmingham. 120,000 shoppers are expected today.
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A large tent has been put up around the area while investigations continue.
The kind gesture touched the hearts of many who shared and retweeted words of support for the officer on Twitter.
Two workers were forced into a back office as the robbers tried to force their way into a safe, police say.