LUBLIN, Poland — Polish Internal Security Agency officers detained a student at the Catholic University of Lublin on suspicion of preparing a mass attack at a Christmas market, government spokesman Jacek Dobrzyński said in a post on X.

“Officers of the Internal Security Agency detained Mateusz W., a student at the Catholic University of Lublin, suspected of preparing a mass attack at one of the Christmas markets, which he planned to carry out using explosive materials,” Dobrzyński wrote. He added that the suspect had been “acquiring knowledge about methods of independently producing materials that were to be used to carry out a terrorist act.”

According to the post, the suspect also “planned to join a terrorist organization to obtain assistance in implementing the intended actions,” and the alleged goal was “to intimidate many people, as well as to support the Islamic State.”

Dobrzyński said that during the operation, ABW officers “seized data storage devices and items related to Islam,” and that a court decided the suspect “will spend the next three months in custody.” He noted that the investigation is being conducted by the Szczecin branch of the Internal Security Agency under the supervision of the local prosecutor’s office in Szczecin, adding that “the case is developing in nature.”