JOIN US"We are opening an investigation into a terrorist crime," Anders Thornberg, head of Saepo's security unit, said a day after an apparent car bomb and a separate blast targeted Christmas shoppers in the Swedish capital.
The suspected bomber, whose identity has not been made public, was killed but Thornberg told a press conference that it was unclear if he had intended to blow himself up.
"If this was a suicide attack, it would be new in Sweden," he said.
"This is very serious and we are doing everything we can to investigate this," he said.
Two people were injured when a car packed with gas canisters exploded around 5:00 pm yesterday in the busy shopping street of Drottninggatan. A second blast occurred shortly afterwards a few hundred metres away, killing the man.
Swedish television reported that a bag filled with nails had been found near the body.
The consequences of the attack "could have been truly catastrophic," Foreign Minister Carl Bildt said on Twitter.
Stockholm police said patrols would be stepped up in the wake of the attack, which comes six weeks after Saepo raised the security alert level from low to elevated.
Germany, Britain and France all raised their alert levels last month amid increased fears of possible terrorist attacks in Europe.