North Yorkshire Police say a number of schools in the county have received bomb hoaxes this morning.
It is understood the hoaxes are part of a national incident.
The schools received an email threatening an explosive had been placed on their grounds and would be detonated if a cash payment was not received.
It is not yet known if any schools in Richmondshire received a hoax warning.
North Yorkshire Police said in a statement: “We have had a number of reports this morning about a bomb hoax at many of our schools across the county.
“This is believed to be a national issue.
“Our Cybercrime Unit Detectives, supported by local officers, have looked at these incidents and it is not believed there is any genuine threat.
“We are working with schools to offer reassurance and address any concerns.”
Both the Home Office and the Department for Education advised any schools that receives the email to contact their local police force – even though a version of the email that has been posted on Twitter warns the schools not to.