The first of the Norwegian schools to receive the warnings warning was Gjerpen Primary School in the county of Telemark in southern Norway, reports national broadcaster NRK. 400 students were evacuated after the head teacher took a telephone call at 9:15am advising of a bomb on the premises.

At 9:24 a similar call was received by Charlottenlund Primary School in Trondheim, and then at 9:26 by Nordnes School in Bergen and slightly later Kvarstein Primary School in Agder. With the exception of the Trondheim school, evacuations were carried out in each case.

Meanwhile, Egtved school near the town of Vejle in southeastern Denmark also received a call warning of a bomb at just before 9am.

It is not currently clear whether the calls were related. The threat in Denmark was, however, made by a man speaking in English, reports Danish broadcaster TV2.

“The threat was made by an English-speaking man and it was probably recorded and played down the ‘phone. That is our impression at least, since the message just continued when our secretary tried to ask about the threat,” Egtved School head teacher Villy Raahauge told TV2 Syd.

Similarly to the Norwegian schools, Egtved school was evacuated, in this case by following a standard procedure for such situations. Bomb disposal units and police bomb detector dogs then combed the school grounds.

Southeast Jutland Police later confirmed to TV2 that the incident was a false alarm and that they would be investigating the incident.

“A number of schools in Norway have been subject to similar [bomb] threats in the same space of time, and there may be a connection and the same person sending the threats. This will be investigated,” Gisle Småge, operation leader in Norway’s southeastern police district, told NRK.

Småge declined to elaborate on the content of the threats themselves.

“I can not go into detail on that. We need time to investigate the case,” he said.