A school bus and a car were involved in a crash on Macs Reef Road.
NSW police said the crash occurred at 4.10pm on Wednesday afternoon in Sutton.
Police now say 40 school children were on the bus, after earlier information that 10 students were on board. None of the children were injured.
The driver of the car, described as a man in his 40s, was transported to Canberra Hospital with serious but non-life threatening injuries.
Officers from Monaro Police District have begun an investigation into the crash.
NSW police are calling on members of the public who have any information on the incident to call Crime Stoppers on 1800 333 000 or to report online via the NSW Crime Stoppers website.