Transcript for Stockholm police believe suspect in custody is driver of deadly truck attack

We do move on to another developing story right now. The investigation into that deadly attack over in Sweden. A stolen truck plowing through a crowded street filled with shoppers slamming into a store ultimately killing four people. Investigators are treating this as a terror attack and ABC's chief foreign correspondent Terry Moran is right there in Stockholm. Terry, good morning to you. Reporter: Good morning, Dan. This morning police sources are telling local media here in Stockholm that there was a homemade unexploded bomb in that truck that barreled through this crowded shopping district killing four people. Leaving more than a dozen others injured. And shocking this tolerant placid city to its core. This morning, Swedish police say they've got their man. One person in custody in connection with the violent truck attack that left four dead and more than a dozen others injured here. Police arresting a man matching the suspect scene in these security images saying they believe he was involved in what authorities have declared a terrorist attack. I saw eight people get derived over. Reporter: According to police Friday afternoon the suspect stole a delivery truck from a nearby restaurant. Minutes later just before 3:00 P.M. That truck is seen on this security video barreling past shops as bystanders scatter. Just eight stores down it slammed into the side of ahlens department store before bursting into flames. There were bodies on the ground everywhere and a sense of panic. People standing by their loved ones but also people runing away. Reporter: Rescuers rushed to help those hurt in the attack as authorities put the city on lockdown to search for the driver. In this difficult moment, Swedish authorities including police and hospitals are doing everything they can to save lives and maintain our safety. Reporter: Overnight the Swedish prime minister spoke to his people and sent a powerful message to the country. Terrorists can never defeat Sweden. Never. Reporter: Right now no evidence that the driver of that truck was linked to any wider plot or terrorist organization. But for years ISIS has been encouraging its followers here in Europe and in the united States to act alone and they specifically mention this kind of ramming attack which is so cheap, so simple and so deadly. Paula. All right, Terry, thank you for your reporting. Now to the major headline

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