In the early morning of 9 April, the gunners at Oscarsborg Fortress fired on the leading ship, Blücher, which had been illuminated by spotlights at about 04:15.
Pada pagi hari tanggal 9 April, para penembak di Benteng Oscarsborg menembaki kapal utama, Blücher, yang telah diterangi oleh lampu sorot sekitar pukul 04:15.