Carl Williams, Headteacher at Moreton School in Wolverhampton, has described an incident in which 20 pupils were jabbed with a diabetic testing needle as "frightening".
Some of the children have been taken to hospital for hepatitis jabs as a precaution.
An 11-year-old boy has been arrested.
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Feeling less cold than recent days with winds easing and some long sunny periods. Most areas will be dry throughout.
A cold start with some icy patches. Largely dry and sunny through the day, with any showers soon dying out and winds easing too.
Scattered wintry showers during the evening will become fewer and further between overnight, with westerly winds tending to ease.