A group of vandals caused havoc when they attempted to board a train then spray painted the side of the carriage.
A group of up to 20 young people attempted to board the 5.14am Bristol Temple Meads to Severn Beach service on Monday, but were too late.
Several members tried to stop the train doors from closing and were then verbally abusive to staff who attempted to reason with them.
Other individuals then spray painted the side of the carriage - covering the windows and panels in silver and pink paint.
The service was cancelled, and all passengers were asked to alight from the train.