STOCKHOLM, April 8 (Xinhua) -- A stolen truck rammed into people on a central Stockholm street before crashing into a department store on Friday, killing four and injuring 15 others. "Everything indicates that this is a terror attack," Swedish Prime Minister Stefan Lofven said at a press conference.
The attack put Stockholm, another capital city in Europe, under terror threat following Paris, Brussels, Berlin and London, adding pressure to the already fragile security situation in the continent.
The attack is particularly frightening as it struck the capital of a nation known for peacefulness and safety. It also shows that the map of terrorist attacks in recent years has expanded from Western Europe to Northern Europe, which is considered one of the safest havens in the world.
Police have arrested a man in Marsta, north of Stockholm in an operation on Friday night. The man, who had minor injuries, said he is guilty of the attack in Stockholm, according to the Swedish paper Aftonbladet. He had reportedly posted Islamic State videos on Facebook.
Police told a press conference that they did not know if this was an isolated incident or whether more could be expected.
This is an alarming trend for the continent, which has already been troubled by a string of terrorist attacks. In the past year alone, Islamic State militants have claimed responsibility for the deaths of more than 100 people in Europe.
The latest attack also follows several other vehicle assaults over the past few months, including the ones in Nice of France, in Berlin and London. Just a little over two weeks ago, an assailant plowed an SUV into a crowd of pedestrians on a London bridge, then stabbed a police officer at the gates of Parliament, killing five people and injuring dozens.
Worry about growing terrorist attacks is prompting tighter border controls for those who enter or exit the 26-country Schengen Zone. The new policy, which was approved last month, was in response to the increase of terrorist threats, the European Council said earlier.
Tough security situation also impacted immigration policy in some European countries. In face of terrorist attacks and other domestic issues, even German Chancellor Angela Merkel, who has been considered to be immigrant-friendly, has been making efforts to curb illegal migration, as shown in her March visit to North Africa.
Analysts say the worsening security situation in Europe demands a long-term resolution, and more coordinated efforts need to be done to ease the growing tension and bring back peace and safety.