In less than 15 minutes, 30% of the zoo population was killed on the first day, and on the second day the aquarium building was completely destroyed by a direct hit. Of the eight elephants, only one survived, the bull Siam, and 2-year-old hippo bull Knautschke was saved from the gunfire in his animal house. Most damage was done during the Battle of Berlin: from 22 April 1945 onwards, the zoo was under constant artillery fire of the Red Army. Heavy fighting took place on the zoo area till 30 April, and safety measures forced the zoo keepers to kill some predators and other dangerous animals.