According to the Basque Government's Department of Security, the Ertzaintza (Basque police) received a call at 4:38 AM regarding a fight in the Ribera de Deusto, specifically on Ramal de Olabeaga street.

The caller informed the Ertzaintza about an assault between two individuals inside a building, on the second floor. Both Ertzaintza officers and emergency medical services were dispatched to the scene. The victim, a 47-year-old man of Sub-Saharan origin, was treated on-site by a dispatched ambulance and did not require hospitalization.

The victim sustained cuts to his left hand and face, allegedly inflicted by the detainee. Police officers entered the building and located the alleged assailant on the second floor.

The Ertzaintza proceeded to arrest the 30-year-old man, of Maghrebi origin, on charges of assault with a bladed weapon. A search of the premises uncovered the knife believed to have been used in the assault. The detainee was taken to police facilities for processing before being handed over to judicial authorities.