Headmaster Peter Hauser wrote to parents on July 17 informing them of the two incidents on successive days the week before.

The first incident on Friday, July 13, saw a year 12 boarding student at a rugby training camp hit the ground, dislocating a vertebra and fracturing a disc. The school's head sports medic was on the scene and ensured the boy was kept immobile until an ambulance arrived.

The student was taken to Toowoomba Base Hospital and later flown to the Princess Alexandra Hospital for surgery. Mr Hauser wrote that the boy's surgery had been successful and he was expected to stay in hospital for four to eight weeks.

In the second incident, on Saturday, July 14, a year 12 day student suffered a similar injury during a trial rugby match against Brisbane Grammar School.

The second boy had surgery on Saturday at the Royal Brisbane and Women's Hospital, and was out of intensive care and walking with the help of a walker by Monday.

Mr Hauser's letter said representatives from Rugby Australia and the Queensland Rugby Union had contacted both boys' families and were working on support programs for both.

Mr Hauser said it was very rare for such injuries to occur "at any level of rugby union", and the last time the school had such an incident was in 2011, and before that 2005.

Thanking staff members of both Toowoomba Grammar and Brisbane Grammar for the care shown to both boys, Mr Hauser said staff had been impressed by the boys' resilience and positive attitudes.

"I ask for the entire school community to think of the boys and their families during their recovery," Mr Hauser said.