The community of Port Lincoln is in shock after a popular father drove himself and his two young children off the end of a wharf in the coastal South Australian city at high speed.

The bodies of Damien Little and his children were found in the submerged car by police divers after the car went off the wharf on Monday morning.

Key points: Police think Damien Little deliberately drove off the wharf with his children in the car

Police think Damien Little deliberately drove off the wharf with his children in the car Locals said Mr Little was respected and well-liked in the community

Locals said Mr Little was respected and well-liked in the community People have laid floral tributes at the scene of the tragedy

The white station wagon sank in up to 30 metres of water, with police saying the incident appeared to have been a murder-suicide.

They said a rifle had been recovered from the car.

Family of the deceased look at tributes at the Port Lincoln wharf. ( ABC News: Candice Marcus )

Friends of Mr Little, who asked not to be named, described him as a "top bloke" and someone who was always ready to help others.

They said his elder boy had been a "bubbly, energetic" child who was a joy to be around.

Lincoln South Football Club president Brenton Dennis said Mr Little was respected and well-liked and had been heavily involved in the football community.

"You couldn't have asked for a better bloke," he said.

"I've been involved with him through football and I know both families — it's just something that you hear about elsewhere and the way it's touched our community here it's just indescribable."

Mr Dennis said the community was struggling to come to terms with the tragedy.

"I think everyone is pretty gutted and distraught and bewildered by what's happened," he said.

"It's just numbed the whole community. I just ask everyone give the families all their love and respect and space that they need at this time.

Onlookers at the wharf at Port Lincoln paid their respects to the family of the deceased. ( ABC News: Candice Marcus )

"I also ask everyone that you think about how our lives are at the moment and just put ourselves in their position and let's all make a promise to never let this happen again."

Commissioner for Victims' Rights, Michael O'Connell, said police should be given time to investigate before any conclusions are drawn.

"One of the things I do caution against is that we jump too soon into blaming the victim and blaming Damien," he said.

"We don't know the motivations, we don't know the reasons behind this incident."

Mr O'Connell said there were options to help people who witnessed the incident who may be traumatised, including a Victim Support Service in Port Lincoln.

'Our hearts go out to Mel'

A white station wagon was pulled from the waters at Port Lincoln. ( ABC News: Deane Williams )

Football club president Mr Dennis expressed his deepest sympathies to Melissa Little, the children's mother.

"Our hearts go out to Mel. I wouldn't want anyone to be in the position she's in at the moment," he said.

"It's just tragic and our hearts are with them and they're in our thoughts and our prayers."

A Lincoln South Football jumper was left as a tribute to the Little family at the Port Lincoln wharf. ( ABC News: Candice Marcus )

Grieving community members visited the wharf late into the night to remember the victims and lay flowers at the scene.

People were in tears as they reflected on the tragedy.

"They're a tight family, they're a really close family so it's going to really affect them pretty bad," local woman Lynette Pycroft said.

Port Lincoln Mayor Bruce Green said it had been one of the community's saddest days.

"People are really just digesting the enormity of the tragedy and thinking about ways of supporting the family and friends of the people involved," he said.

"That's going to be hard and it's terribly, terribly sad.

"We don't have much knowledge about the background to this, we just know it's a huge loss to our community."

An investigation is being led by detectives from the Major Crime Investigation Branch, forensic experts and the Major Crash team, supported by local police.