The incident took place in Fernbank, a town along the nation's southern coast about 160 miles east of Melbourne. A bus was carrying a group of teens to an unreported destination when it left the roadway and came to rest in a ditch laying at a 45-degree angle, the Daily Telegraph of Sydney said.
Twenty of the students and the bus driver suffered injuries, ranging from broken bones to head and neck injuries. Six of the victims remain listed in serious but stable condition after the crash. The rest have been treated and released.
Police said the cause of the accident is under investigation.