STOCKHOLM — A truck crashed into an upscale department store in central Stockholm on Friday, killing at least two people, according to Swedish Prime Minister Stefan Lofven, who said all indications were that it was a terror attack. One person was arrested.

People in the downtown area fled in panic, and the country’s intelligence agency said a large number of people were injured. Swedish radio put the death toll at three.

“Sweden has been attacked,” Lofven said. “This indicates that it is an act of terror.”

Swedish broadcaster SVT said shots were fired at the scene, though it wasn’t clear by whom and police said they could not confirm that.

Live television footage showed smoke coming out of the upscale Ahlens department store on Drottninggatan Street, which the truck smashed into. The department store is part of Sweden-wide chain. The building includes several stores at street-level.

“We stood inside a shoe store and heard something … and then people started to scream,” witness Jan Granroth told the Aftonbladet daily. “I looked out of the store and saw a big truck.”

Photos from the scene showed a beer truck sticking out of the department store, and Aftonbladet daily reported that Swedish beer maker Spendrups said one of its trucks had been carjacked earlier Friday.