Citizens in Chile are getting back to normal after a nationwide power outage affected millions of people and a "state of emergency" gets lifted as officials point fingers at energy providers.

Most residents had power restored by midnight but the situation remained unstable. President Gabriel Boric blamed power companies for not acting faster.

"We were like sardines in the dark," one passenger described the moment their underground train stalled. Many of those who had been in lifts inside the stations when the power cut happened had to be freed by firefighters. One woman in her 70s was trapped in a lift between two floors in a building in Santiago.

Chile's foreign ministry said on Wednesday it is "monitoring" a U.S. probe looking into potential new tariffs on imports of copper, a metal critical to electric vehicles, military hardware, the power grid and many consumer goods.