The police in Turku, in western Finland, said that they had shot and apprehended a man on Friday after several people were stabbed and that they were clearing the city centre as they searched for more potential suspects.
Eyewitnesses reported hearing gunshots and told YLE, the Finnish national broadcaster, that they had seen a lifeless body on the ground.
The police have reinforced security at the airport and at train stations in Helsinki, about 100 miles to the east, in response to the attack, The Associated Press reported.
Wali Hashi, a journalist who witnessed the episode, said he saw a group of people chasing a man with a knife screaming "God is great" in Arabic after a woman was stabbed. "I was shocked and terrified to see such horrible incident," he said.
A resident of Turku told YLE that she had been 20 meters away from where the knife attacks took place, in Salutorget, a main square in the city of more than 180,000 people.
"We heard a young woman scream at the corner of the square," the resident, identified as Laura Laine, said. "We saw a man at the square, a knife flashing and waving in the air. I understood that he had stabbed something."
It was not clear whether this case was connected to series of terrorist assaults claimed by the Islamic State across Europe, most notably the deadly attacks in and around Barcelona on Thursday and Friday.
 "Rescue personnel cordon the place where several people were stabbed, at Turku Market Square, Finland Photo: Reuters")