The incident took place at Tesco, in Great North Road, at 10pm. Two men entered the shop armed with a knife and a crow bar. They threatened staff and demanded money from the tills before leaving with more than £900. Detective Constable Karin Peters said: This was a frightening ordeal for the staff and Id urge anyone with information to call us, or Crimestoppers anonymously, as a matter of urgency. Id like to remind the public not to approach these men, but to contact us with any information. Anyone with information is asked to call police on 101, or Crimestoppers, anonymously, on 0800 555111.