"This was an incredibly nasty incident and the staff were very shaken but fortunately unharmed, which is our number one priority.
"We will be offering them any assistance and any support they require after this terrible incident.
"We are also working with the police and hopefully witnesses will come forward to help catch these people."
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The family of a teenager who was stabbed to death as he walked home from college in Chelmsford say they are inconsolable.
Dry and chilly overnight. Winds strengthening Sunday and becoming milder.
Dry with some sunshine but a cold wind.