At least two people were killed Friday when a large beer truck slammed into an upscale department store in a busy Stockholm pedestrian mall Friday in what Swedish Prime Minister Stefan Lofven calls an apparent "terror attack."

Lofven says at least two people were killed in the attack, while state broadcaster SVT says at least five people were dead.

The prime minister says one person was arrested after the truck slammed into the Ahlens store around 3 p.m. in Drottninggatan (Queen Street), one of the city's main pedestrian malls.

The truck had careened down the street at  high speed for several blocks, leaving a trail of broken glass, tire tracks and bodies the newspaper Dagens Nyheter reports.

Witness Jan Granroth told the daily Aftonbladet that “we stood inside a shoe store and heard something ... and then people started to scream.” He says “I looked out of the store and saw a big truck.”

One witness, 66-year-old Leander Nordling, tells Aftonbladet that he was standing in the perfume department at Åhlens when he heard a loud bang.

"It sounded like a bomb had exploded and began to smoke heavily in through the main entrance," he said. He said he and other customers and staff took shelter in a storage room.

Swedish beermaker Spendrups said its truck had been carjacked earlier Friday, the daily Aftonbladet reports.

"During a delivery to (a) restaurant, and while the driver was unloading, someone jumped into the driver’s seat and drove off with it," Spendrups communications director Marten Lyth told TT Swedish news agency.

Aftonbladet says all government offices were locked down following the incident.

Contributing: Associated Press