A small truck careened into a crowd of people before crashing into an upscale department store Friday in Stockholm, the latest in a series of recent attacks in Europe that have used vehicles as a weapon.

Swedish Prime Minister Stefan Löfven said the incident appeared to be a terror attack, the Associated Press reported. Swedish authorities said the attacker has not been arrested.

But the Swedish Security Service stopped short of calling the incident terrorism. In a statement on the service’s website, officials said they were trying to identify the attacker and whether one or more people were responsible.

“We are treating it as an attack, without specifications,” Nina Odermalm Schei, a spokeswoman for the security service, told CNN.

Ekots reporter fångade kaoset efter att en lastbil kört in i folkmassa i centrala Stockholm https://t.co/i3Ij9rgcW7 pic.twitter.com/0saPOiWuCC — SR Ekot (@sr_ekot) April 7, 2017

People are seen running from the scene of the attack in Stockholm.

Around 3 p.m. local time, the driver reportedly veered into the sidewalks along the Drottinggatan Street, one of Stockholm’s busiest pedestrian areas, before driving through the front window of Ahlens department store.

Swedish police told the BBC that at least two people had been killed in the incident, with many injured.

“No hospital would disclose information about the number of people they received, but they have gone up in disaster mode, which is the highest position,” Swedish radio station SR Ekot reported on Twitter.

The city was put on lockdown after the incident, The Guardian reported. Parliament as evacuated, and all trains in and out of the city center were halted.

The incident is the second major fatal attack by vehicle this year in Europe. (In late March, a French man tried to drive a car into crowds in the Belgian city of Antwerp, but there were no injuries, The New York Times reported.)

On Twitter, former Swedish Prime Minister Carl Bildt called the tactic “the latest terrorist method.”

Steal a lorry or a car and then drive it into a crowd. That seems to be the latest terrorist method. Berlin. London. Now Stockholm. — Carl Bildt (@carlbildt) April 7, 2017

Last month, 52-year-old Khalid Masood, a native of England, rammed a car into the pedestrian walkways on Westminster Bridge before crashing in front of Parliament, killing five and injuring around 40. He stabbed a security guard before being fatally shot by police.

In July 2016, a man plowed a truck through pedestrians celebrating Bastille Day along the waterfront in Nice, France, driving for a mile before opening fire and being fatally shot by police. In December, a Tunisian man pledging allegiance to ISIS crashed a truck into a Christmas market in Berlin, killing 12 people and injuring nearly 50.