Police in Bosnia announced on Thursday the arrest of an 18-year-old man who threatened on social media to copy the gun attack in which a student from Serbia killed eight classmates and a school guard on Wednesday, Reuters reported.

Law enforcement forces of the Bosnian Croat-Muslim Federation detained a suspect in the western city of Bihac on charges of creating a threat to security and terrorism on the orders of the Una Sana cantonal prosecutor’s office, a police spokesman told the agency.

The teenager was identified only by the initials A.Z. It appears that he had a history of threats and intimidation in social circles, but last year the criminal case against him was closed due to the fact that he was a minor.

The mixed secondary school in Bihac, where AZ attended, released a statement urging students and parents not to panic over the threats, revealing authorities had been informed of the situation.

“That guy who killed eight children is a mega king for me. I have been preparing something similar for an economic school in Bihac for a long time. It will be an unprecedented massacre in Bihac, I swear on my life!” the young man wrote on his Instagram account, Agerpres quoted.