STOCKHOLM — A man drove a stolen beer truck into a crowd of people in a popular shopping district in Stockholm on Friday afternoon and then rammed it into a department store, killing four people and injuring 15 others in an attack that unleashed bloodshed and panic on the streets of another European capital.

“Sweden has been attacked,” Prime Minister Stefan Lofven said in a televised news conference. “This indicates that it is an act of terror.”

A nationwide manhunt conducted through much of the evening ended when the police “caught one person of particular interest,” said Jan Evensson, the chief of regional police. On Saturday, a spokesman for the police, Lars Bystrom, said the man in custody was believed to have driven the truck.

Image A picture showing a man wanted in connection with the truck attack in Stockholm was released by the Swedish police on Friday. Credit... Stockholm Police

The first emergency call came in around 2:50 p.m. local time as the truck mowed down pedestrians along Drottninggatan, a busy pedestrian shopping street. The truck, stolen just blocks away earlier in the day, came to a stop after slamming into the entrance of the Ahlens department store. Photos from the scene showed a billowing cloud of black smoke rising from the store.

The attack struck the heart of a nation known for its peacefulness and tolerance, and turned a warm spring afternoon into a scene of terror.

“I saw hundreds of people running. They ran for their lives” before the truck crashed into the department store, a witness identified only as Anna told the newspaper Aftonbladet.

Katarina Libert, 32, a freelance journalist, was trying on clothes at the department store when she heard a boom and the walls shook.