Hoax bomb threats made to seven primary schools in Northern Ireland
Police are investigating a possible connection between hoax bomb threats made to schools in Northern Ireland and England.
On Tuesday, seven primary schools in Northern Ireland received the threats.
It follows similar hoaxes in England on Monday.
The Northern Ireland schools received calls between 09:00 and 10:00 BST, claiming explosives had been left at their premises.
A number of schools were evacuated and the PSNI said they were "investigating a series of malicious communications".
Ch Supt Garry Eaton said police responded immediately and worked with the schools "to establish what the circumstances of the calls were and to put appropriate procedures in place to ensure the safety of both pupils and staff".
"What I can say is that we believe all seven schools received hoax calls - we've checked all the schools and we don't believe there were any devices left at the schools," Ch Supt Eaton said.
"But nevertheless, it's a very serious and worrying situation."
He added: "Some of the schools took the decision to move pupils out, others didn't. Obviously that's a matter for the schools."
Ch Supt Eaton said the PSNI "will be working closely with our colleagues in GB to establish if there is a definite connection and how we take the investigation forward".
He said a link is "a strong line of enquiry", adding that it was "very coincidental that following those calls yesterday in GB, we receive similar calls today".
Earlier, police said there was nothing to indicate the calls were terrorist-related.
One of the schools threatened was Bloomfield Primary in Bangor, County Down.
DUP MLA Peter Weir, who is on the school's board of governors, said: "The school received malicious calls this morning, they were extremely threatening and violent in their nature.
"The staff then reacted very swiftly and professionally and evacuated the school, but this must be still extremely traumatising for the children concerned."
Dawn Walsh, whose daughter is in P5 at the school, said: "I think it's absolutely disgraceful, at the end of the day these kids are just trying to get an education.
"Anybody who can do this to kids is, in my eyes, disgusting."
In a statement, the Education Authority said it had been "made aware of malicious communications to a number of schools today".
"Schools have in place policies and procedures for dealing with such incidents," it added.
"They have been working closely with their local PSNI officers and taking the relevant precautionary measures to ensure the safety of all children."
Police in Scotland have said that a telephone threat to schools there "does not appear to be credible" but is "being taken seriously".