The entire state is without power after being lashed with severe storms. (Video courtesy ABC News 24)
Traffic lights were rendered inoperational, choking roads in the CBD. Building fire alarms blared across the city, according to local media reports, and residents rushed to supermarkets to stock up on candles and matches.
By 7.30pm local time, power had been restored to some Adelaide suburbs including Gilberton, Hallett Cove and Kensington. It had been reported earlier that much of the state could be without power until 4.15am on Thursday.
More than 18,000 State Emergency Services volunteers were on the ground across the state responding to hundreds of calls for help, with reinforcements on their way from Western Australia.
Premier Jay Weatherill said the storm took down three transmission lines and nine towers in the Port Augusta region, forcing the electricity connection between South Australia and Victoria - known as an "interconnector" - to be shut down.
Wind turbines, which make up an estimated 40 per cent of the state's power generation, were unable to operate as winds were too high, South Australian senator Nick Xenophon said.
Mr Weatherill told media it was the "usual protocol" to isolate South Australia from the National Electricity Market in a situation where there is a "large frequency drop".
He said the state's "backup baseload generation" was beginning to restore power, however that was a gradual process.
The operators of SA's high-voltage power network, ElectraNet, were in an emergency meeting on Wednesday afternoon to determine a solution.
National energy and resources minister Josh Frydenberg said high-voltage transmission towers were blown over in the state's north as lightning struck a power station, creating a "perfect storm".
"The combination of these events, and indeed other events, have led to a frequency surge, an electricity surge, across the interconnector," he said.
He proposed bringing together the nation's energy ministers as soon as possible in a Council of Australian Governments meeting to determine what happened and ensure it was not repeated.
Adelaide Airport was able to run on back-up power after a brief blackout, but travellers were told to expect delays.
About 5.30pm, residents were told to conserve power to their mobile phone battery and prepare for extended outages. Residents were also told to switch off all heating, cooking and other appliances that were in use when the power went out.
Two severe storm fronts swept across SA on Wednesday, the first hitting Adelaide around lunchtime and the second about 3.30pm. The power went out across the state about 3.45pm, when there was heavy rain, lightning and thunder over the capital.
The town of Cleve, on the central Eyre Peninsula, was among the hardest hit. Other towns including Gawler, Kapunda, Clare and Balaklava were also hammered by the storm, which dumped large hail over the region.