Two people died on Tuesday following a knife attack at an Islamic centre in the Portuguese capital Lisbon that wounded several others, police said.
Prime Minister Antonio Costa said it was "premature to make any interpretation of this criminal act."
"Everything points to this being an isolated incident," he told reporters.
Images on Portuguese television showed armed police outside the Ismaili Muslim centre.
"The attack left several people wounded and, for the moment, two dead," police said in a statement, adding that the suspected assailant had been shot and arrested.
Police said they arrived at the building just before 11 am (1000 GMT) after being warned that a knife attack was underway.
"The police come across a man armed with a large knife. Orders were given to the attacker to cease the attack, which he disobeyed, advancing towards the police, knife in hand," the police statement added.
"Faced with the serious and ongoing threat, the policemen used firearms against the person, hitting and neutralising the aggressor."
The Shia Imami Ismaili Muslims, generally known as the Ismailis, belong to the Shia branch of Islam, according to their website.
The Ismaili Muslims a "culturally diverse community" living in over 25 countries around the world, it says.
There are around 7,000 Ismaili Muslims living in Portugal, a nation of around 10 million people.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)
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