Bush pilot Dick Lang and his son Clayton were killed in a bushfire on Kangaroo Island after fighting fires for two days.

The body of 78-year-old Mr Lang was believed to have been found in their vehicle on Playford Highway at Gosse while his 43-year-old son was found some distance away.

The pair had been out fighting the blaze and were returning to a family property when they became trapped.

In a statement on Saturday afternoon, the Lang family said the pair had been returning to a family property after fighting a blaze nearby for two days.

The family paid tribute to Mr Lang, known as "Desert Dick", who opened up the outback to countless travellers from Australia and overseas, flying tourists to all corners of the country.

"He loved the bush, he loved adventure and he loved Kangaroo Island," they said.

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His youngest son, Clayton Lang, 43, was one of Adelaide's leading plastic and reconstructive surgeons specialising in hand surgery.

CFA

There have been no other reports of people missing or other injuries but three fire crews endured burnovers in their trucks.

A watch and act warning remains in place for the fire which has now destroyed more than 100,000 hectares including large parts of the Flinders Chase National Park.

Earlier, Premier Steven Marshall said the deaths were tragic news.

"Our hearts go out to the families of those people who have been affected," he said.

#Bushfire Advice Message : Issued for #PLAYFORD_HWY/WEST_END_HWY_,_RAVINE #fire. If you are in this area stay alert, monitor local conditions and decide what you will do if the situation changes. #BAM ID=0004441 #SAFires https://t.co/aB21Cur6gt pic.twitter.com/Sx269PAlBN — Country Fire Service (@CFSAlerts) January 3, 2020

"It really does reiterate the very important message that people listen to the alerts. This a very dangerous situation on Kangaroo Island."

Significant property losses are expected from the fire with major damage to tourism and other infrastructure also likely.

About 500 firefighters will continue to battle the blaze over the weekend, with crews and other resources brought in from the SA mainland.

The fire had been burning since late in December but escalated dramatically on Friday when it jumped containment lines during hot and windy conditions.

At one stage the entire island was subject to either an emergency warning or a watch and act advice with only the towns of Kingscote and Penneshaw on the east coast considered safe places.

By Saturday morning the situation had eased with cooler conditions providing an opportunity for fire crews to work on establishing fresh defences.

However, CFS chief officer Mark Jones said it was expected the fire would continue to burn for several days.

Mr Marshall said the government had already appointed a community recovery officer and would look at what additional support islanders would need in the coming days.

"It's clear that South Australia has had an extraordinarily difficult time with extensive damage right across our state," he said.

"Our focus at the moment is doing everything that we possibly can to contain the fire on Kangaroo Island.

"But very quickly our focus will move onto recovery."

Mr Marshall said he had also spoken to Prime Minister Scott Morrison on Saturday with the PM offering "all the support that is required".

At one stage on Friday, the blaze threatened the towns of Parndana and Vivonne Bay, which were evacuated, but both were spared any major damage.

The luxury Southern Ocean Lodge on the island's west coast was not so lucky, suffering structural damage, though the owners said all guests were moved to Kingscote or Adelaide before the threat intensified.

Six staff stayed to monitor the situation and activate the facility's emergency plan but all had since been accounted for and were not injured.

The operators of the Sealink ferry service said up to 300 people were currently at a relief centre in Kingscote seeking passage to the mainland and would be transported over the next two days.

The operators of the Kangaroo Island Connect ferry had also offered their services to move people off the island.

The CFS said the blaze remained uncontrolled and still posed a threat to people and property with conditions on the fire ground continually changing.