Police are conducting an operation in several parts of Ostrołęka, Poland, following a knife attack at a local secondary school. Viewers of Polsat News reported the evacuation of a building on Hallera Street. The Main Police Headquarters confirmed the evacuation due to the discovery of suspicious substances within the building. The evacuated building was the residence of a 19-year-old male suspected of carrying out the knife attack at the school in Ostrołęka. Authorities are currently investigating both the attack and the nature of the substances found. The incident has prompted a significant police presence throughout Ostrołęka. Further details are currently unavailable.