More than 400 schools in England have received a hoax email threatening to detonate a bomb on school grounds if money is not handed over, police said.
A number of schools were evacuated, but police said there was no evidence the threats were terror-related.
Schools in London, Manchester and North Yorkshire were among those affected.
The email appeared to come from gaming firm VelpPVP, but the company said the account had been “spoofed” and the message had not come from them.
Schools and colleges in Cumbria, Cambridgeshire, East Yorkshire, Hertfordshire, Lincolnshire, West Midlands, Derbyshire, Avon and Somerset and Northumbria were also targeted.
Humberside Police said 19 schools in its area reported receiving the threat.
Det Supt Tony Cockerill, from the force, said: “We have spoken to all schools who have contacted us, reassured them that there is no need to evacuate and offered them security advice.”
Greater Manchester Police’s Assistant Chief Constable Vanessa Jardine said she understood parents and the general public would be very concerned, adding: “I want to assure you that we are working closely with all of the schools to ensure the safety of pupils and staff.
“We are carrying out extensive enquiries to understand the full circumstances and although there is not currently believed to be any direct threat, as with any report of this nature, they are all being thoroughly investigated.”
A North Yorkshire Police statement described the threat as a “hoax”, adding: “Our cybercrime unit detectives, supported by local officers, have looked at these incidents and it is not believed there is any genuine threat.”
Both the Home Office and the Department for Education, meanwhile, are advising any school 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.
The email address requested payment to an email address that used the domain veltpvp.com, but the website posted messages on Twitter denying any involvement.
Sarah Stephenson was at her son’s school, Oathall Community College in West Sussex, waiting for a meeting when it was evacuated.
“I noticed a little bit of activity going on. I went through to student support and all of a sudden a notification went out that the school was being evacuated.
“My son George was in class at the time. The students were evacuated out of the school building and told to ring their parents. An email was sent out to all the parents.”
Another affected school, Dowdales secondary in Cumbria, tweeted: “As you may know the school office received a threatening email this morning.
“The decision was taken to evacuate the school as a precaution. Students and staff are safe and have returned to normal lessons.”
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