The raid was requested by members of the Danish resistance movement in the hope of freeing imprisoned members and destroying Gestapo records. Britain initially turned down the request as too risky, due to the location in a crowded city core, but eventually approved it in early 1945 after repeated requests.
The very low-level attack consisted of 20 Royal Air Force de Havilland Mosquito fast bombers in three waves, escorted by 30 RAF North American Mustang fighters. Unfortunately, a Mosquito in the first wave hit a lamp post and crashed into a boarding school beside the Shellhus, and the third wave of bombers attacked the burning school thinking it was their target. 125 Danish civilians died in the school, including 86 schoolchildren.
The raid succeeded in destroying Gestapo headquarters and severely disrupting Gestapo operations in Denmark, as well as allowing the escape of 18 Gestapo prisoners. 55 German soldiers, 47 of the Gestapo's Danish employees, and 8 prisoners died in the headquarters itself. Four Mosquito bombers were lost, and nine crew members died on the British side.