Poland on Thursday said it arrested a Ukrainian man for killing one person and wounding four others in a knife attack on the grounds of a Catholic abbey in the country's southeast.
Police said a 31-year-old man went on a stabbing spree at the 17th-century abbey in Jaroslaw, some 30 kilometres (19 miles) from the border with Ukraine.
Authorities said they were working to clarify the circumstances of the incident in which the man, a citizen of Ukraine, had attacked four men and a woman with a knife.
The local Gazeta Jaroslawska newspaper published images of fire engines and police outside the monastery, with its entrance cordoned off.
Poland, a close ally of neighbouring Ukraine, has taken in hundreds of thousands of Ukrainians fleeing Russia's invasion -- with some social tensions erupting in recent months.
Spokespeople for the police and prosecutors confirmed to AFP that one of the victims had died.
While Polish media have reported that the deceased person was a priest, neither police nor prosecutors confirmed the victim's identity to AFP.
Stabbings -- especially at religious sites -- are extremely rare in Poland, one of Europe's most Catholic countries.
"At around 9.30 am (0730 GMT), the police received a report that a Ukrainian national had attacked men with a knife on the grounds of Jaroslaw Abbey on Benedyktynska Street in Jaroslaw," police in the southeastern Podkarpackie region said in a statement.
All the wounded victims were taken to hospital, with some having serious wounds, it said.
"I came for the holy mass," one witness, an unnamed Polish woman, told Polish TV station TVN.
"A man aged around 30 struck the priest in the neck artery. The priest fell to the ground," she said.
TVN also quoted a nun, Barbara Dendor, as saying the clergy could not "get our heads around what has happened today".
"It is a place that I believed was safe," she said.
Regional and district prosecutors were sent to the scene of the crime, local authorities told AFP.
No motive for the attack was given.
Poland has said that Russian-orchestrated sabotage is on the rise in the NATO country, during a fifth year of war in neighbouring Ukraine.
The NATO and EU member state along the alliance's eastern flank has become the main hub for transporting Western military and humanitarian support to Kyiv.
Earlier this month, Prime Minister Donald Tusk warned that intensifying Russian attacks in Ukraine in the coming weeks could affect Poland.