HELSINKI, Finland -- Police in Finland say the man who's in custody in a deadly stabbing attack in the western city of Turku is likely to have acted alone, but they are not ruling out the involvement of other people.

Authorities are looking for more potential suspects.

They say the man stabbed eight people, killing two of them, before police shot him in the thigh and detained him. Authorities are trying to determine his identity and nationality.

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Finland's interior minister says security is being stepped up across the country.

The country's president, Sauli Niinisto, visited Turku later Friday and condemned what he called a "shocking and cowardly act." He said officials are doing what they can "so that all Finns are able to feel safe."

A suspect -- who police said was "a youngish man with a foreign background" -- was being treated in the city's main hospital but was in police custody. Security was being stepped up across the Nordic country, Interior Minister Paula Risikko told reporters at a news conference.

Police did not give any information on the two people killed or the conditions of those wounded in downtown Turku, 106 miles west of Helsinki, the capital.

The country's top police chief, Seppo Kolehmainen, said it was too early to link the attack to international terrorism.

"Nothing is known about the motives ... or what precisely has happened in Turku," he said.

Several people were seen lying on the ground in Puutori square in central Turku, according to Finnish broadcaster YLE. On Twitter, police urged people to avoid that part of Turku.

Tabloid Ilta-Sanomat says six people were injured, one man and five women, and that a woman with a stroller was attacked by a man with a large knife.

Prime Minister Juha Sipila said the government was closely monitoring the ongoing police operation and holding an emergency meeting.

Witness Laura Laine told broadcaster YLE that she stood approximately 65 feet from where the stabbing took place.

"We heard that a young woman was screaming. We saw a man on the square and a knife glittered. He was waving it in the air. I understood that he had stabbed someone," Laine was quoted as saying.

Finnish television channel MTV said security had been heightened at Helsinki's international airport but didn't give details.

"Police have told us not to go to the city center so we are in this coffee shop a few blocks away from the city center," said Vanessa Deggins, an American who is studying business in one of Turku's three universities. She didn't witness the actual attack, but heard sirens going past.

"This is a safe country by American standards. I have gone home alone at 2-3 a.m. ... I feel safe. This is a safe country."