Transcript for Swedish truck attack suspect may have had bomb in vehicle

Turning to Sweden. A country still in shock over a truck attack mowing down pedestrians in the capital. A 39-year-old suspect under arrest and investigators examining a device they say was found inside the truck. The country's prime minister paying his respects at a ma make-shift memorial. Terry Moran with the latest. Reporter: It was Sweden's moment of terror. A stolen beer truck suddenly transformed into a massive weapon, barreling down a crowded shopping street. There were bodies on the ground everywhere, and a sense of panic. Reporter: And today, we know the man authorities say was behind the wheel, seen here in grainy security camera images released while he was on the run after the attack. He's 39 years old, originally from Uzbekistan in central Asia, known to security services here as a possible islamic extremist, based on his social media posts, but he wasn't being monitored. And this today, he may have had a bomb in that truck. We have found something in the truck, in the driver's seat, a technical device which should not be there. Reporter: Overnight, a raid in a Stockholm suburb, several people detained for questioning. The suspect, who authorities haven't named, isn't talking, and the investigation continues. We do not know whether there are further persons involved in this act, or not. Reporter: Four people were killed in the attack. Ten remain hospitalized, including a child. The attack shut down central Stockholm for hours and it shocked the people of this normally placid country to their core. Today they're erecting this all too familiar makeshift memorial which we're seeing in city after city across Europe. And now a grim pattern is clear. Trucks and cars, so ordinary, so ubiquitous, increasingly weaponized by terrorists. Nice, in France, last July, a slaughter on bastille day, 86 dead. Berlin, christmastime, 12 murdered. Just last month in London, 5 killed. And now, Stockholm. Terry Moran ABC news, Stockholm.

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