The homemade bomb was hidden in a locker at Østbanehallen and the explosion caused extensive damage to the station.
[1] Eight days after the attack, another bomb was found in the station's ticket hall, which had 2 kg more explosives.
His fingerprints matched identically with the station bombing incident, and he later admitted carrying out the attack.
His motive for the bombing was to extort the Norwegian State Railways (NSB) for money.
He was also convicted of 30 other criminal offences, including theft, vandalism, shootings and also a plan to bomb a train track at Ekeberg.