A man stabbed people at a mall in Poland on Friday, killing one person and injuring seven others, AP reported. The attacker, identified as a 27-year-old Polish citizen, has been detained.

The attacker was a resident of Stalowa Wola town, the site of the attack. “He used a knife,” PAP news agency quoted regional police spokesperson Anna Klee as saying. “He was attacking people from behind, hitting them with the knife,” Klee said.

The attacker “acted irrationally and could not explain the motives for his actions,” National Police spokesman Mariusz Ciarka said.