Farmers on Kangaroo Island were shooting fire-injured sheep on Sunday as the small community prepared for more dangerous days ahead when hot weather returns in the middle of the week.

Firefighters on the island have been battling fires since before Christmas that blazed out of control after extreme weather on Friday.

The fires, which are still burning, started at the western end of the 160km-long island, and have burned about a third of it, killing two people and devastating the island’s two main industries, tourism and farming.

The former pilot Dick Lang and his son, Clayton Lang, were killed when fire overran their car on Friday.

Ferries have been running almost around the clock to evacuate thousands of tourists back to the South Australian mainland, the former mayor Jayne Bates said.

Bates lives in Penneshaw, which is on the east of the island closest to the mainland and hosts its ferry terminal.

Most of the tourist attractions are at the western end of the island.

They include the luxury Southern Ocean Lodge, which has been destroyed by fire, and the Flinders Chase wilderness area.

Bates said a large number of farm buildings had also been destroyed.

“A lot of our blokes have gone out today to destroy injured sheep – you’re talking thousands,” she said.

“They’re digging pits.”

This image made from video shows dead kangaroos and sheep after bushfires hit Kangaroo Island. Photograph: ABC via AP

The fires were “the worst we’ve ever had”, she said.

“We had a big one in 2007 but not to this extent.

“And the loss of the two lives – well.”

The fire had also destroyed at least $20m worth of bluegum and pine trees on plantations run by Kanagaroo Island Plantation Timber.

On Friday KIPT said it was still assessing the damage, but at least 13% of its forests had been burned.

The company said it would try to salvage wood from the areas that have already burned by bringing forward harvesting.

Also damaged in the fire was the Middle River Water Treatment Plant, prompting SA Water to urge island residents to limit non-essential water use.

About 600 properties remained without power on Sunday, with SA Power Networks working to restore services.

“It was unfightable,” Bates said of the fire.

“Is this our new normal? That’s the fear.”

She said the fires were “greatly subdued, but we’re in for some warmer weather midweek”. Temperatures were forecast to reach 32C degrees on Wednesday and 37C degrees on Thursday.

“I don’t know what’s going to happen.”

Fire crews from Adelaide have relieved tired local volunteers, but Bates said locals would be keen to handle the mop-up.

She said tourists were evacuated to Penneshaw before boarding Sealink ferries to the mainland.

“This is our very busiest peak time, this is when the influx comes,” she said.

“There were 10 or 11,000 people here in total – that’s a bit of a guess.”

Quick Guide Climate change and bushfires Show Does climate change cause bushfires? The link between rising greenhouse gas emissions and increased bushfire risk is complex but, according to major science agencies, clear. Climate change does not create bushfires, but it can and does make them worse. A number of factors contribute to bushfire risk, including temperature, fuel load, dryness, wind speed and humidity. What is the evidence on rising temperatures? The Bureau of Meteorology and the CSIRO say Australia has warmed by 1C since 1910 and temperatures will increase in the future. The Intergovernmental Panel on Climate Change says it is extremely likely increased atmospheric concentrations of greenhouse gases since the mid-20th century is the main reason it is getting hotter. The Bushfire and Natural Hazards research centre says the variability of normal events sits on top of that. Warmer weather increases the number of days each year on which there is high or extreme bushfire risk. What other effects do carbon emissions have? Dry fuel load - the amount of forest and scrub available to burn - has been linked to rising emissions. Under the right conditions, carbon dioxide acts as a kind of fertiliser that increases plant growth. So is climate change making everything dryer? Dryness is more complicated. Complex computer models have not found a consistent climate change signal linked to rising CO2 in the decline in rain that has produced the current eastern Australian drought. But higher temperatures accelerate evaporation. They also extend the growing season for vegetation in many regions, leading to greater transpiration (the process by which water is drawn from the soil and evaporated from plant leaves and flowers). The result is that soils, vegetation and the air may be drier than they would have been with the same amount of rainfall in the past. What do recent weather patterns show? The year coming into the 2019-20 summer has been unusually warm and dry for large parts of Australia. Above average temperatures now occur most years and 2019 has been the fifth driest start to the year on record, and the driest since 1970. Is arson a factor in this year's extreme bushfires? Not a significant one. Two pieces of disinformation, that an “arson emergency”, rather than climate change, is behind the bushfires, and that “greenies” are preventing firefighters from reducing fuel loads in the Australian bush have spread across social media. They have found their way into major news outlets, the mouths of government MPs, and across the globe to Donald Trump Jr and prominent right-wing conspiracy theorists. NSW’s Rural Fire Service has said the major cause of ignition during the crisis has been dry lightning. Victoria police say they do not believe arson had a role in any of the destructive fires this summer. The RFS has also contradicted claims that environmentalists have been holding up hazard reduction work. Photograph: Regi Varghese/AAP

Visitors have been asked not to come to the island unless it is essential.

“Most tourists want to visit our beautiful iconic sites – and of course there’s no access to that end of the island,” Bates said.

“It’s best to give us all a bit of breathing space and then come back later.”

The state government has appointed the wildlife official Mike Williams to lead the recovery. The National Parks and Wildlife Service senior executive was named the local recovery coordinator to support islanders as they come to grips with their needs over the coming weeks and months.

“This is an unprecedented tragedy for the Kangaroo Island community, who are now facing a recovery effort on a scale never seen before on the island,” the SA human services minister, Michelle Lensink, said.

“His appointment recognises the unique challenges facing Kangaroo Island as it embarks on the process of recovery, including geographic isolation, losses relative to population, impacts on local economic activity and community wellbeing.”

with Australian Associated Press