Yobs first set fire to a car in Stoke Gifford at around 1AM on Sunday 3rd April with others later terminally damaged in Bradley Stoke, Little Stoke and Patchway.
The attack on the Rolls Royce carpark in Patchway destroyed 15 minibuses which were used by schools and vulnerable members of the community.
It is believed the minibuses were owned by charity Four Towns and Vale Link Community which helps people with mobility issues while it also supports on school runs. Some of the vehicles written off were meant to take students to and from school the very next day.
Bradley Stoke mayor and town council spokesman Tom Aditya told the BBC that the attacks were "appalling and shameful".
Mr Aditya said that this sort of crime was "unheard" of in Bradley Stoke.
There have been no reports of injuries or damage to buildings and it is not believed that any arrests have yet been made.