Brisbane's Anglican Church Grammar School (Churchie) is grieving over the death of one of their most loved teachers, who jumped to his own death after tossing his 2-year-old son off Story Bridge in a shocking scene that was witnessed by several people yesterday.

Jason Lees, 40, was an esteemed prep teacher and a successful international rugby referee. His toddler son went to kindergarten also at Churchie.

Police told the media that Mr. Lees left home at about 2:30am Monday and drove his son to Kangaroo Point. They rode a bicycle to the outbound side of Story Bridge, and it was there that the father tossed his son off the bridge before plunging to his death.

Mr. Lees and his son fell from the bridge about 3.20am, with their bodies later located in Captain Burke Park at Kangaroo Point.

Det-Supt Michael Niland told the media several people witnessed the tragedy.

Churchie headmaster Jonathan Hensman said the school had a day of "shock and sadness."

"Jason was a highly regarded and much loved teacher whose kindness to his students, his gentlemanly approach and enthusiasm for teaching were acknowledged by students, parents and staff alike," he told the Herald Sun.

Churchie is one of Brisbane's most exclusive schools.

Mr. Lees taught at Churchie since 2007. He was based for six years at The Southport School, where he was the 1st XV rugby coach.

Regional crime co-ordinator Detective Superintendent Michael Niland, who spoke to Brisbane Times, would not confirm whether the deaths were being treated as a murder-suicide. He simply said it was "a tragedy."

Asked if Mr. Lees was in a relationship with the child's mother and whether they lived together, Superintendent Niland said the matter is still under investigation.