The 22-seater was carrying 13 tourists travelling from Colac to Melbourne when it turned and landed on its roof. The group, from Hong Kong, were set to return home on Sunday. 

Air ambulance arrived on scene at about 4pm to take one seriously injured patient to the Royal Melbourne. 

Ambulance Victoria spokesperson John Mullen said three others were taken to Ballarat Base Hospital via road ambulance for treatment, with a bus expected to take the remaining nine also to Ballarat. 

Police on scene said seat belts would have saved more passengers from injuries. 

Enfield resident Anthony was driving home when he saw the bus lose control after coming around the bend. 

He turned into Woodlands Road to hear the bus roll and turned to see the impact, before quickly calling 000. 

Neighbour Travis Curtain was first on scene, running outside to the bus after he heard the noise. 

He said it took less than one minute to get the passengers safely out of the bus, with the injured passenger taking longer. 

"I've lived here five years and there hasn't been any other accidents on this corner that I know of," he said. 

"It is a bit uneven when you come around the corner."