A major power outage crippled several of Argentina's provinces on Wednesday, including large parts of the Buenos Aires metropolitan area, plunging millions of people into darkness for at least two hours as summer temperatures soared.
Total electricity demand nationwide dropped by around 40 percent at the time of the power failure, which officials said was equivalent to more than six million households or 20 million people.
The massive outage, which hit around around 4.30pm local time, affected large swathes of the Buenos Aires Metropolitan Area (AMBA), hitting several neighbourhoods in Buenos Aires City and large parts of the Conurbano, the populous region that encircles the capital.
Users on social networks also reported widespread power cuts in Mendoza, Santa Fe, Córdoba, Neuquén and several other provinces.
In the capital, the lights flickered back on at about 6pm local time in the underground Subte system and public services were gradually restored.
Reports of the first outages began after 4pm, with traffic lights out of order and Buenos Aires metro stations in total darkness.
The power cuts were caused by a fire on a power line, local outlets reported.
The fire, on a high-tension line outside the Buenos Aires metropolitan area, triggered a safety system to kick in and turn off several power plants and lines, according to a government spokeswoman. Engineers rushed in to fix the line and reconnect millions nationwide, with most users gradually having their service restored.
The outages extended from the capital to other industrial and residential hubs in the centre of the country, as well as provinces in the northwest, along the Andes, and as far south as Santa Cruz in Patagonia. Plants out of service included major state-run nuclear facilities Atucha I and Embalse.
Local TV station Todo Noticias reported that the grid was unable to meet 40 percent of electricity demand.
Energy Undersecretary Santiago Yanotti told the C5N news channel that power demand had soared due to the high temperatures. In Buenos Aires, it reached 36 degrees Celsius (97 degrees Fahrenheit) on Wednesday.
"The blackout is large, affecting several provinces. At a time of high temperature as it was today in much of the country, the electricity sector demanded 25,000 megawatts and there was a cut that removed about 9,000 megawatts. This caused the system to break down," said the official.
The power cut is believed to have been caused by a fire in a field near high-tension lines connected to the Atucha 1 nuclear power plant, confirmed Yanotti.
The plant, along with the Central Puertos power plant, was taken offline as a safety precaution, sparking widespread problems nationwide, the country's national nuclear power authority Nucleoeléctrica said.
In a note sent Wednesday night to the Federal Court of Campana, which has jurisdiction in the region where the fire took place, Economy Minister Sergio Massa called on judges to “investigate, prosecute and, if necessary, arrest those responsible for the very serious acts that could fall under the crimes of arson and havoc," as he expressed his "certainty about the intentionality" of what happened.
There was no immediate official data on the numbers of households affected, but a government source told AFP that Cordoba, Santa Fe and Mendoza provinces along with Buenos Aires experienced outages.
In the capital, power outages were reported in Colegiales, Villa Lugano, Parque Patricios, Mataderos, Palermo and Caballito, among others.
Electricity failures were also reported in the provinces of Jujuy, Salta, San Luis, Tucumán, La Pampa, La Rioja and Santiago del Estero.
Argentina has been suffering heat waves in the past few weeks that cause electricity usage to soar as households and businesses crank up air conditioning. The National Meteorological Service says Buenos Aires City has recorded its hottest summer in more than a century of record-keeping.
Blackouts are not uncommon for residents in and around the capital, with years of price controls leading to insufficient investment in power grids.
The last major national blackout was in 2019.