The man was arrested on Friday afternoon in Uppsala and will probably be interviewed on Friday evening over the threats made in an internet chat room.

“When the man is interviewed the details will be forwarded to the prosecutor in Örebro who will then decide if he can be detained for the threat against the school,” Carlsson said.

According to police the man contacted local Örebro newspaper Nerikes Allehanda to seek a ransom payment in return for calling off his his threatened massacre.

The newspaper reports that the man demanded that they help him contact the police and threatened to carry out the threat if he did not receive the multi-million kronor pay off.

When the threat became known school staff decided to evacuate the school buildings without delay.

The would-be attacker explained in English in a post on the forum that he planned to go to the school and kill pupils with a AK 4 and grenades.

The pupils were described as sinners and warned that they should be punished. The poster then declared an intention to commit suicide after the attack.

“This type of prank is just stupidity that creates concern. Many worried parents have got in touch with us,” said Torbjörn Carlsson at Örebro police said while the search for the man continued on Friday.

The threat was taken seriously from the outset and was classified as distinct from others of its kind due to its precision including details of the proposed weapon, ammunition, timing and location.