In a series of alarming events in Stockholm, six individuals have been apprehended in connection with a recent explosion at an apartment building in Gärdet and a hand grenade incident in Gamla Stan.

The explosion, which occurred early on a Sunday morning, damaged a building entrance but caused no injuries.

The suspects are believed to be linked to an extortion case involving former business executive Joachim Kuylenstierna, who was threatened to pay 100 million kronor to a criminal network.

The hand grenade, found in late October, was safely detonated by the national bomb squad.

Among those arrested, five have been detained, while the sixth, a minor, has been handed over to social services.

The police have issued warnings to individuals with the surname Kuylenstierna, as the threats appear to target them indiscriminately, regardless of their connection to Joachim Kuylenstierna.