A series of “malicious communications” have been made to schools across Northern Ireland, police have said.
The Police Service of Northern Ireland (PSNI) said there was no information to indicate a terrorist link to the incidents.
Officers said there had been similar communications in other parts of the UK and police services were working together to establish if there was a link.
PSNI Temporary Chief Superintendent Simon Walls said: “PSNI are investigating a series of malicious communications to schools across Northern Ireland today.
“At this stage there is no information to suggest the incidents are terrorist-related. However, enquiries continue to establish the facts.
“We will liaise with other UK police services, who have received similar calls, to investigate who is responsible and whether these incidents are linked.”
He urged anyone with information to contact police on the non-emergency number 101 or call Crimestoppers anonymously on 0800 555 111.