"We condemn the attack in Stockholm. My thoughts are with the families of the deceased & prayers with those injured," he tweeted. "India stands firmly with the people of Sweden in this hour of grief," he added.

A truck crashed into an upscale department store in central Stockholm today, killing at least two people.

"Sweden has been attacked," Swedish Prime Minister Stefan Lofven said, adding "This indicates that it is an act of terror." One person was arrested.

Swedish broadcaster SVT said shots were fired at the scene, though it wasn't clear by whom and police said they could not confirm that. Live television footage showed smoke coming out of the upscale Ahlens department store on Drottninggatan Street, which the truck smashed into.