Police shot and wounded a suspect after a stabbing spree in which a man killed two people and wounded six others in the Finnish city of Turku.
Within hours of the attack on Friday the force had announced increased police patrols across the country.
“There are eight victims in the stabbing. Two dead and six injured,” Turku police tweeted after the assault in a market square. A hospital official told journalists that all the victims were adults.
Police shot a suspect in the thigh minutes after the attack at another square nearby, arresting him and confiscating his knife.
His identity has not yet been established, police said late Friday, nor was the motive for the attack clear.
Police described the suspect in custody as “a young man of foreign origin”, providing no other details except to say they were collaborating with the Finnish Immigration Service.
While security forces wrote on Twitter that police were “looking for other possible perpetrators”, police told journalists it was likely there was only one attacker.
The stabbing spree comes with Europe on high alert a day after drivers slammed vehicles into pedestrians in two attacks in Spain, killing at least 14 people and injuring more than 100 others. The Islamic State (IS) group has claimed responsibility for the Barcelona attack.
In Turku, images of a body covered in a white blanket were published on some online news sites, including the local daily Turun Sanomat.
The attack took place in the heart of the port city in southwestern Finland, just after 4:00 pm (1300 GMT) in a bustling neighbourhood.
“The perpetrator stabbed two people on the market square, one of whom came to the aid of the other,” police told reporters.
“I saw an old woman, I tried to help her. She was bleeding all over her body,” Wali Hashi, who witnessed the attack, told AFP.
Another witness, who did not want to give his name, told public television YLE: “A young woman screamed really loudly at one corner of the square. We saw a man on the square, with a knife in his hand and he was waving it.”
Central Turku — located about 140 kilometres (90 miles) from the capital Helsinki — was swiftly cordoned off and stores and restaurants closed.
Police also tweeted that they had raised their emergency readiness across the country after the stabbing, increasing security at airports and train stations and putting more officers on the streets.
“The number of patrols is being increased, information gathering is intensified,” they wrote.
Investigators from Finland’s National Bureau of Investigation were also examining surveillance camera footage from the scene.
Prime Minister Juha Sipila tweeted that his government was “following the situation in Turku closely and the police operation underway”.
Turku mayor Aleksi Randall said in a statement it was “difficult to understand that such violence would happen on this scale in Turku.
“Occurrences that have been all too frequent in Europe and around the world have now arrived here, which is what we’ve been afraid of, too.”
President of the European Commission Jean-Claude Juncker said the EU “strongly condemns” the attack.
It said at the time it saw an increased risk of an attack committed by IS.
“Supo has become aware of more serious terrorism-related projects and plans in Finland,” it said.
“Foreign terrorist fighters (who have) left from Finland have gained significant positions within IS in particular and have an extensive network of relations in the organisation,” it said in its June assessment.
In 2012, Finland’s then-prime minister Jyrki Katainen escaped a knife attack in Turku while campaigning for municipal elections.
The man who approached him carrying a knife was found to be psychologically disturbed and no charges were brought against him.