Schools in Leeds were forced to go into lockdown after receiving threats of violence against children and staff by email.
At least six schools have adopted precautionary measures after receiving an email directly or being warned by the police or the council earlier on Thursday.
West Yorkshire Police later confirmed a person has been arrested on suspicion of a malicious communications offence in connection with the incident.
Headteachers told parents that schools were under “soft” lockdowns, meaning pupils will remain inside with gates, doors and windows closed. Schools have alsourged parents to be vigilant when collecting their children.
Beeston Primary School posted on Facebook: “Following information from Leeds City Council health and safety team about a credible threat to all schools in Leeds, Beeston Primary School has ensured that any necessary precautions in school have been made.
“All gates remain closed and locked, as usual, and staff are being extra vigilant. We have well-rehearsed procedures for lock down in place should we need them and a robust CCTV system covering all school grounds which is being closely monitored.”
A letter from Sharp Lane Primary School told parents that “they have no further information about the threat” but assured them it had not been made against the school directly.
It read: “Following information from police about a credible threat to all schools in Leeds, Sharp Lane Primary School has implemented a ‘soft invacuation’ procedure.
“This means that all children will be kept indoors for the full day. All gates remain closed and locked as usual and doors and windows within school will remain closed all day.
“We have no further information regarding the threat at this time but please be reassured that Sharp Lane Primary School has not received a direct threat, and the children and staff are safe.
“Please can we ask you to be vigilant when picking up your children at the end of the day.”
Other schools affected included Richmond Hill Academy, Ruth Gorse Academy, Windmill Primary School and Clapgate Primary School.
Gildersome Primary School posted on social media: “Some parents may be aware of a threat that has been made to some Leeds schools this morning.
“To reassure you, staff are being extra vigilant and we are following our normal safeguarding procedures to ensure the school site is secure.
“If there is any update or changes we will contact all parents and carers. Please do not call school at this time except in an emergency as we need to keep the phone lines clear.”
It comes after several schools across in the north-west of England were placed in lockdown on Monday having also received threatening emails.
At least three schools in Manchester and two schools in Chester were affected after the “malicious” communications were sent, thought to have threatened harm to students and staff.
Investigations were launched by both Cheshire Police and Greater Manchester Police forces and officers were sent to schools to “provide reassurance” during pick up time, police said.
A spokesman for West Yorkshire Police said: “Police are aware of an email which has been sent to a number of schools in Leeds and Bradford today.
“The contents of the email are being investigated by police and officers are providing reassurance and safety advice to affected schools.
“Officers have commenced an investigation into a potential malicious communications offence and have now made an arrest in connection with the matter.”
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