An experienced pilot and his son have been killed in catastrophic bushfires that have ravaged more than a third of Kangaroo Island and destroyed homes and businesses.

Key points: Dick Lang and his son Clayton died in the blaze, the men's family has confirmed

Dick Lang and his son Clayton died in the blaze, the men's family has confirmed Significant property losses are expected on the island

Significant property losses are expected on the island A cool change came through South Australia last night

The family of tour operator and aviator Dick Lang has confirmed he perished in the blaze, along with his youngest son Clayton — a leading plastic surgeon who specialised in hand surgery.

Dick Lang, 78, ran his own flight adventure business out of Adelaide Airport and was described as one of the nation's "best bush pilots".

"We are devastated to have lost two beloved members of our family — Dick Lang and his youngest son Clayton Lang — in such terrible circumstances," his family said in a statement.

Plastic surgeon Mr Clayton Lang also perished in the fire that killed his father. ( Dextra Surgical )

"Dick and Clayton were in the process of returning to the family property on Kangaroo Island after fighting a nearby fire for two days."

Dick Lang lived and worked in the outback for most of his life, securing him the nickname 'Desert'.

His 43-year-old son was supervisor of surgical training at the Queen Elizabeth Hospital, his family said.

Dick Lang — whose ancestors were among the first European settlers in South Australia and arrived on the Buffalo — had flown rescue operations in desert regions and over Papua New Guinea.

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

"Dick and Clayton were prominent members of the South Australian community who rose to the top in their chosen professions."

Police said the men died on the Playford Highway in the centre of the island, and that one of the victims was found inside a car.

More than 170,000 hectares — which is more than a third of the island — have been burned by two major bushfires.

The Country Fire Service (CFS) said most of the damage had been done by a fire which started near Ravine in the island's north-west, which had burned about 155,000 hectares and was described as "virtually unstoppable".

Pilot and tour operator Dick Lang died in the Kangaroo Island fire. ( ABC News )

Dick Lang's family said he had been married to his "beloved wife" Helen for more than 55 years and said he had four sons and seven grandchildren.

"Helen and the family are heartbroken and reeling from this double tragedy and are touched by people's thoughts at this difficult time," it said.

"We would like to extend our sincere thanks to the CFS volunteers, police and members of the Kangaroo Island community who are doing so much to help all those on the Island affected by these catastrophic fires."

There were gasps of shock at a community meeting on the island in Kingscote when police confirmed the two deaths.

Hundreds of people later stood for a minute's silence, and SA Premier Steven Marshall has also expressed his condolences for the victims.

"Very tragic news for South Australia as we learn this morning that two people have died in the fires," he said.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 17 seconds 17 s Kangaroos flee a massive blaze on Kangaroo Island.

Prime Minister Scott Morrison has announced 3,000 Australian Defence Force reservists will be deployed to fire recovery across the nation, including some on Kangaroo Island.

"[A taskforce] will be stood up for South Australia particularly focusing on Kangaroo Island at present," he said.

Mr Marshall said he had spoken to Mr Morrison this morning, and said the 9th Brigade based in Adelaide was poised to help.

The Premier said all buildings in the Flinders Chase National Park had been "very extensively" damaged.

"The fires that occurred yesterday were significantly worse than in 2007 in Flinders Chase because they took out all of the building infrastructure," he said.

The ruins of a house after a bushfire ripped through on Kangaroo Island. ( Supplied )

SA Tourism said there were unconfirmed reports of damage to local tourism assets including the island's Visitor and Information Centre, the KI Wilderness Retreat and Hanson Bay Wildlife Sanctuary.

The threat on the western half of the island was downgraded to an advice message, but the Ravine fire is still out of control.

Fire expected to continue to burn for days

There were concerns the Ravine fire would merge with another in the middle of the island as weather conditions deteriorated on Friday, but that fire at Duncan has since been contained after burning 18,000 hectares.

Mr Marshall said Vivonne Bay on the island's south coast had been evacuated during the fire crisis but the blaze was prevented from spreading to the township.

Southern Ocean Lodge on Kangaroo Island after fire ripped through. ( ABC News )

About 350 personnel were fighting the fires overnight, including those from the State Emergency Service, the Metropolitan Fire Service and the Department for Environment and Water.

That has since increased to 500 firefighters, and the state's emergency centre has been activated.

"The weather today should give our crews the opportunity to start to get on top, although we expect that the fires will burn for some days," CFS chief officer Mark Jones said.

"During yesterday's dramatic fire conditions, the Turkey Lane airfield from which our bombers operated had to be evacuated and aircraft relocated to Kingscote.

"I would emphasise to everyone this is not over. The fire season is in its infancy."

A weather station at Western River on the island's north coast has recorded evidence of the intensity of the Ravine blaze.

Western River weather station recorded an apparent temperature of 428C. ( Bureau of Meteorology )

The station yesterday recorded a reading of 99.9 degrees Celsius and an apparent temperature of exactly 428C as the fire ripped through.

The Bureau of Meteorology said it had not been able to confirm the condition of the temperature sensor, which is continuing to emit readings, but believes it has been severely damaged.

Fires on Kangaroo Island have been burning for more than two weeks, after initially breaking out on December 20 — the same day as the Cudlee Creek blaze in the Adelaide Hills.

Locals urged to limit water use

Residents on the island have been asked to limit any non-essential water usage, because of fire impacts of the Middle River Water Treatment Plant.

Loading

SA Water said delaying activities such as washing laundry and watering lawns would help preserve water storage levels to ensure enough was available for drinking and responding to spot fires.

Many properties on the island are currently without power.

There is a relief centre at the Kingscote Football Club, where hundreds of people have gathered.

SeaLink, which operates the ferry between Penneshaw and Cape Jervis, said up to 300 people at the Kingscote relief centre were waiting to be taken back to the mainland.

The company said it was working to transport those people as a priority.

SeaLink said all non-essential travel to the island should be deferred, and offered full refunds to anyone with a ticket.

Tourists and locals are leaving Kangaroo Island on the SeaLink ferry from Penneshaw. ( ABC News: Claire Campbell )

Cruise & Maritime Voyages Australia's Vasco da Gama cruise ship was due to dock in Penneshaw on Saturday but instead is staying off the coast with 1,267 passengers on board.

"The escalating, uncontrolled bushfires burning on Kangaroo Island means our scheduled anchorage call to Penneshaw has understandably been cancelled," managing director Dean Brazier said.

"We have, however, offered to provide evacuation assistance if required for the locals and tourists who remain on the island.

"As a result, the ship has proceeded to Penneshaw and is anchored a safe distance from the coast to be on standby this morning to assist with a possible evacuation plan to the mainland."

An unknown number of properties have been destroyed by the fire. ( Supplied )

Operators of the Southern Ocean Lodge near the Flinders Chase National Park said the resort suffered "significant damage".

There had been concerns the central town of Parndana might be lost, but the CFS said it appeared to have been saved.

"Anecdotally, we believe a finger of fire may have come close to Parndana, but again until we can get some eyes on the ground in the daylight we believe Parndana has not been impacted by the main front of the fire," state duty commander Nick Stanley said.

Hundreds of firefighters have responded to the island's bushfire crisis. ( Facebook: Leon Bignell )

Cool change reduces threat

Mr Stanley said a welcome change came through last night.

Loading

"Once we saw those conditions ease around midnight–1am we saw the southerly impact start to slow down and with that the relative humidity came up to around 85 per cent across the island so that did significantly help with the decreasing the fire behaviour," he said.

He said the rain had "greatly assisted" in dampening the fire's ferocity.

"Crews are able to get a bit closer and deal with the active fire edges rather than having to go into asset protection mode so hopefully that moderation in fire behaviour allows them to get some good work done today," he said.

The Environment Protection Authority has rated western Adelaide's air quality as poor and fair in eastern, southern and northern Adelaide, as smoke drifts from Kangaroo Island across the city and areas to the north.

The air quality in Port Augusta, Port Pirie and Whyalla is currently rated as poor.

Department for Health and Wellbeing chief public health officer Nicola Spurrier said people with chest or heart conditions should stay indoors when smoke or dust is present and follow their personal health management plans.

"We appreciate that many people will want to open their doors and windows to help cool down their homes but we recommend keeping doors and windows shut while there are still high levels of smoke and dust in the air," Associate Professor Spurrier said.

A CFS crew looks towards the fire ground on Kangaroo Island on Friday evening. ( ABC News )

Meanwhile, crews have worked through the night to contain a fire that sparked at Kersbrook in the Adelaide Hills early yesterday evening.

About 150 firefighters, 25 fire trucks, four bulk water carriers and two heavy plant machines worked to bring the 20ha blaze under control.