Norwegian police arrested the mother of the three men suspected of detonating an explosive device outside the US Embassy in Oslo on Sunday morning.
The woman has been held on suspicion of being connected to the explosion, the police said in an emailed statement on Friday, without providing further details. All four will be presented to be remanded in custody at Oslo District Court later on Friday, according to police.
Police said on Monday that an improvised explosive device was left at one of the entrances of the embassy early on Sunday, with the resulting blast causing only minor damage and no casualties.
A video depicting Iran’s late Ayatollah Ali Khamenei was posted on the Google Maps website at about the same time as the blast outside the diplomatic mission, the police said earlier, adding that it was probing a link between the incidents.