The vehicle rolled and almost ended up in a river while passengers made a lucky escape out of the back window.

Nathan Parks from SA Ambulance Service said it was a “confronting” scene.

“We had 25 people on board the bus, and when the first ambulance crew arrived people were still climbing out the back window,” Parks said.

“It could have been a very different outcome when you look at the bus down the embankment.”

The bus was full of passengers when it left Humbug Scrub road, just outside of Williamstown, and rolled at around 9.30am today.

A 21-year-old man was rushed to hospital with neck and spinal injuries.

The other passengers all escaped unharmed.

The bus company, JC Minibuses said it had hired the vehicle out to the group and the driver wasn’t an employee.

“[We are] just really happy that we don’t have any more injuries here, and what we will do now as a company is we will support the renter,” operations Manager JC Minibuses said.

9News has been told the tour group had come from the city and were planning to visit the Whispering Wall tourist attraction ten minutes away.

Emergency services say thankfully everyone onboard was wearing a seatbelt.