A dangerous bushfire that forced the evacuation of towns, destroyed homes and injured more than 30 people on South Australia's Yorke Peninsula was caused by a power network fault.
The blaze broke out during catastrophic fire danger conditions on Wednesday afternoon, and burned uncontrolled in stubble towards the coastal towns of Edithburgh and Coobowie.
The Country Fire Service said firefighters worked throughout the night in difficult conditions to halt the fire's spread.
"(There was) strong winds, high fire intensity, high rates of spread and, in that context, it produced lots of smoke and lots of dust," incident controller Richard de Groot told reporters.
"It was at a point of practically no visibility. There were some fairly stressful moments."
Rhonda Stewart was at the Edithburgh Caravan Park when she and the others on site were told to evacuate just before midnight.
"A lot of the people who were travelling, we all elected to go down to the boat ramp just near the beach," she said.
"Just as it was getting light, around 5 or 6am, light turned to dark and all you could see was smoke.
"You couldn't see the boat ramp, you couldn't see the beach."
Ms Stewart said they returned to the park a few hours later to find the park unscathed but the inside and outside of the caravans covered in soot and ash.
The now-contained fire has burnt through about 5000 hectares over an area with a 61-kilometre perimeter, wiping out "a high number" of stock and crops.
At least 11 properties have been damaged or destroyed, including homes and sheds, and 33 people have been treated for minor injuries including smoke inhalation.
Mr de Groot confirmed the fire was caused by a power network fault just outside of Yorketown.
A cool change that swept across the state on Thursday brought relief for firefighters, who have placed control lines around the blaze.
"With the weather that is forecast over the next few hours, we're quite confident that we'll be in a position to hold this fire overnight and in the coming days," Mr de Groot said.
"The challenges aren't nearly as significant as they were in the early hours of (Thursday) morning."
The Yorketown fire was one of 65 which broke out across South Australia on Wednesday amid soaring temperatures, high winds and dust storms.
A number of those prompted emergency warnings including two north of Adelaide, one in the Barossa Valley and a second fire at Price on Yorke Peninsula where properties may also have been lost.
The Bureau of Meteorology said a number of locations broke November heat records, including Lameroo at 44C, Murray Bridge at 45.3C and Nullarbor at 46.6C.
Supervising meteorologist Paul Lainio said severe fire weather had been forecast for three districts on Thursday, but cooler temperatures, higher humidity and decreasing winds had eased conditions.
"The change will continue to move over the far northeast today," he said.
"Unfortunately, no significant rainfall accompanied today's change."
Mr Lainio said smoke haze from the Yorke Peninsula fire could be seen over the CBD early on Thursday morning but it has now cleared.