The shooting took place in June. As a result, two people were killed and more than 20 were injured.
The arrested men are accused of terrorist collaboration, according to a police communique.
One of the suspects is a man in his 40s with Somali citizenship and the second is a Norwegian national in his 30s, the report added.
A shooting occurred in the vicinity of the London Pub club in June, just the day before the LGTBI (Lesbian, Gay, Transgender, Bisexual, and Intersex) Pride parade, according to information from the NRK channel.
Authorities have since detained four other people.
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