Schools have been placed under “lockdown” following a threatening email sent to pupils and staff members.
Schools in Chester, Liverpool and Manchester all reported similar threatening messages.
One school, Lache Primary School in Chester, said: “Do not come to school, we cannot release your child or allow anyone to enter the building.
“These measures are in place to keep your children safe. We will update you as soon as the police have been back in touch.”
However, they later said they believe the threat to be a “malicious hoax”.
Lache Primary School said: “Working in conjunction with the police, they would like to reassure parents that this is believed to be a malicious hoax.
“Therefore, we are happy to release the children.”
In an earlier email to parents they said the procedure was “precautionary”, adding: “Your children are safe and continuing with learning.”
At around 10.05am on Tuesday, September 12, police were made aware of an email which had been sent to a number of schools in Chester and Ellesmere Port which made threats to pupils and staff.
An investigation has been launched and officers have been attending schools to provide reassurance.
Detective Chief Inspector Justin Hancock said: “We would like to reassure parents that this is believed to be malicious and we are doing everything we can to locate the person responsible for these emails.”
Lache later released another statement, which confirmed there is not currently a threat on the site: “We are aware that parents have arrived outside school. To repeat, we cannot let any children out or any parents in.
“As we have stated this is a precautionary measure following an unpleasant email that has been sent to a number of schools in Cheshire, Liverpool and Manchester. There is NOT a threat on site.
“We have locked down the school to ensure that everyone is safe. Which they are. The police are dealing with the situation and are very happy with the measures that we have in place.”