"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 Children's Laureate Chris Riddell visits Rockland All Saints Community Primary near Attleborough in Norfolk.
Business leaders across our region are calling for reassurance following Brexit. Concern is growing at losing EU money.
Outbreaks of rain this evening will clear overnight. Tomorrow will start dry and bright but there'll be further rain at times later on.