A man in Australia drove off his car into the sea, killing himself along with his two sons after posting a lengthy suicide note on Facebook. The incident occurred in southern Australian in the City of Port Lincoln.

According to police, Damien Little, who was in his 30s, killed himself and his sons by driving his white Ford station wagon into the sea from Brennan's Wharf in Boston Bay. The man's station wagon was travelling at a speed of 80km/hr when it plunged into the sea.

"We saw a car go past and heard a bang. Then it ... flipped over the lip and sunk to the bottom," an eyewitnesses named Bodhi Pannenburg was quoted as saying.

At around 6am local time (7pm GMT) on 4 January, police, ambulance and rescue crew were called to the spot and divers recovered the bodies of Little and his two sons – four-year-old Koda and one-year-old Hunter – from a depth of 30 metres around 12.30pm the same day.

Along with the bodies, police also recovered a rifle from the submerged vehicle. Detective superintendent Paul Yeomans said that the police were not treating the case as an "accident".

Meanwhile, Port Lincoln mayor Bruce Green said: "First there is a sense of disbelief and then it moves to grief. The community will still be digesting the event and coming to terms with the tragedy."

"There's a lot of sensitivities to consider, such as the family and the friends of the family and children. It's obviously a tragedy for the community. Over the next few days as this unfolds on how it happened and who the people were, the sadness and the knowledge will be hurtful in the community," he added.

Little had posted the suicide note on Facebook at 5.45am on 4 January and shared it with wife, AU News reported.

The Samaritans provide free support service for those who need to talk to someone. It can be contacted through Samaritans.org or on 08457 90 90 90, 24 hours a day, 365 days a year. Call charges apply.