Some senior officers have now arrived at the incident and are formulating their plan http://t.co/v1KgmV5Y
More wearers standing by in CP suits. Wearing these is very hard work so BA compressed air cylinders don't last long! http://t.co/vUrwBTtJ
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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.