Cambridgeshire schools have received bomb threats.
The threats have been made to schools across the country, including in Lincolnshire, and are believed to be hoaxes.
A Cambridgeshire police spokeswoman said: “We are aware of a series of malicious communications made to schools across the country, including in Cambridgeshire.
“The investigation is being co-ordinated by the National Crime Agency and the threats are not currently being treated as viable.
“We take hoaxes extremely seriously. They divert police resources and cause disruption and alarm to the public.
“Anyone with information should contact police on 101 or call Crimestoppers, anonymously, on 0800 555111.”