The fortress was subjected to heavy Luftwaffe bombing later on the same day, to which the fortress could only reply with two Bofors 40 mm L/60 anti-aircraft (AA) guns and three Colt M/29 7 mm AA machine guns at Seiersten Battery, as well as another four Colt M/29 7.92 mm AA machine guns at Håøya Battery, Grimnes 1990: 15 but again there were no Norwegian casualties.