Early investigations point towards four people and a white ute spotted around Ballarat Botanical Gardens on Thursday morning

• Follow our Australia news live blog for latest updates
• Get our breaking news email, free app or daily news podcast

Vandals have cut off the heads of the statues of Kevin Rudd and Paul Keating in Ballarat, and damaged 18 others.

A total of 20 busts on Prime Ministers Avenue in the Ballarat Botanical Gardens in Victoria were attacked between 2am and 5am on Thursday. The avenue features busts of Australia’s first 29 prime ministers.

Sign up for Guardian Australia’s breaking news email