There were no injuries reported and it was too early to say how big the blasts had been, a police spokesperson told reporters at the scene.
A shooting occurred outside the Israeli Embassy in Stockholm; no injuries reported, security increased amid ongoing investigations.
According to sources, the issue relates to the unauthorized disclosure of security-related information, but the timeline for informing the soldier remains unclear.
The arrests were part of a large-scale operation carried out throughout the country and in conjunction with various border police units.
The man reportedly set fire to two buildings, before ramming a store with a van and threatening people with machetes.
The suspect, 62-year-old Boaz Gilad, has been arrested and questioned.
Norwegian security police investigate potential links between a Norwegian-owned company and pagers used in recent Hezbollah attacks in Lebanon.