Chile experienced a massive blackout on Tuesday that left an estimated 94% of the country without electrical power. The outage effectively brought the country to a halt, affecting everything from cellphone services to trains, subways, and even the nation’s international airport Arturo Merino Benítez. The government declared a state of emergency and an overnight curfew on Tuesday evening that remained in effect until 6 a.m. Wednesday.

The massive power cut began at around 3 p.m. Chile time and lasted for about 7 hours. The temperature in the capital city of Santiago was close to 30°C at the time of the energy collapse, forcing businesses and state dependencies to suspend operations due to intense heat from the lack of air conditioning. School was also called off for the day. 

By 11 p.m, close to half of those affected had regained electricity. As of this writing, the Interior Minister had reported that 94% of users had regained power, including public services like the Santiago de Chile subway system. The government announced that the state of emergency was lifted at 8.25 a.m. local time. 

The outage also caused problems in Argentina, as the lack of electrical power affected customs offices operating along the country’s borders. A border crossing in southern Argentina called Cardenal Samoré was forced to close on Tuesday, leading to significant traffic jams with personal vehicles and trucks on both sides forced to wait until power was restored. Authorities released a statement on Wednesday announcing that the crossing was now operating normally. 

The Chilean government ruled out the possibility of an attack, attributing the outage to a technical failure. Specifically, officials pointed to a “disconnection in the transmission lines” at an energy plant that power company ISA InterChile operates in the northern part of the country. 

President Boric, however, publicly stated that the incident will be investigated. “It is unacceptable that the lives of millions of people are affected by the irresponsibility of so many companies,” he said while addressing the country Tuesday night. 

“We will not let this slide and will act firmly with companies that have not been up to the task,” he later wrote in a statement published on X.  

According to a press release the company published on Wednesday morning, an “event” affected an electrical transmission line running between Vallenar and Coquimbo at approximately 3.16 p.m Chile time. This incident allegedly caused the country’s entire electrical system to collapse. The release went on to say that staff are looking into what caused the failure, and will assist with any government investigation in to the matter. 

Early estimates suggest that the power outage was the worst in the country’s history, surpassing the 2010 blackout that left 90% of the country in the dark. On March 10 of that year, just two weeks after a massive earthquake had devastated the country, a transformer at a substation in southern Chile failed. The incident interrupted a music concert taking place to raise funds for survivors and trapped thousands of people inside the subways, as 200 trains were halted due to the outage.