On the outbreak of the Second World War in 1939, the animal keepers were issued with rifles to deal with any dangerous animals who might escape if the gardens were bombed. A night shift was introduced to watch over the animals 24 hours a day. A list of dangerous animals that was drawn up included 13 lions, 6 tigers, 2 leopards, 1 cheetah, 2 tigons, 3 other small cats and several bears. Although the zoo's administrators succeeded in convincing the local authorities that any danger from the animals was minimal, primarily because the perimeter walls were so high, the keepers were replaced in their sharp-shooting role by soldiers who patrolled the grounds armed with tommy guns.