The attack occurred on Thursday morning at the abbey, with Polish media reporting that the assailant first stabbed a priest in a nearby cafe before attacking four more people inside the abbey. Police confirmed that four men and one woman were stabbed. The name of the murdered priest has not been released.
Polish President Karol Nawrocki said the attack "has shaken us all and demands a firm response from the state." Prime Minister Donald Tusk vowed the perpetrator "will be punished with the full severity of Polish law."
Ukrainian President Volodymyr Zelensky said the two countries were "shocked by this evil" and called for "a quick and thorough investigation of all circumstances." The Ukrainian embassy in Poland condemned the attack, urging that "pain [not] escalate into hatred or new violence."
Polish Interior Minister Marcin Kierwiński said psychological support was being provided to those affected. The motive for the attack is under investigation.
Poland has seen a number of violent incidents involving its citizens and Ukrainians since Russia's full-scale invasion of Ukraine, which has brought many Ukrainian refugees to Poland.