More than eight million households across Chile were left without power on Tuesday afternoon after an electricity transmission line failed, cutting off the electricity supply to much of the country.

In the capital, Santiago, the entire underground train system was suspended almost immediately. Thousands of people had to be evacuated and stations were plunged into darkness.

"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.

She told local media that she had "kicked the door" of the lift to draw attention to her plight and her screams eventually alerted the concierge.

"I'm brave, I told myself 'I'm not going to die here'," she said.

Videos shared on social media also showed metro passengers using their mobile phones' flashlights to find their way out of dark stations.

According to Metro de Santiago, the evacuation of the underground was completed 90 minutes after the power cut - but disruption caused by the outage carried on for many more hours.

The 150 extra buses deployed to ferry passengers were not nearly enough to make up for the suspension of the metro, which transports an average of 2.3m passengers every day.

Long queues formed at bus stops, where passengers grew increasingly angry when packed buses did not stop.

Their numbers soon swelled with workers sent home early because most offices were paralysed by the lack of electricity.

"The power went out at 3:00pm, so we had no power at all," one shopkeeper in Santiago said. "People started closing up at around 4 or 5pm."

Traffic in the capital was further disrupted by the failure of several traffic lights.

A truck collided with a car at one crossing where the traffic lights were out and there were reports of at least one other accident also caused by the lack of functioning traffic lights.

With the gridlock getting worse, thousands of people were forced to walk to their destinations in summer temperatures of around 30 Celsius (86 Fahrenheit).

One of them, Sharon Ortiz, a 28-year-old waitress, told AFP news agency that the public transport system had "collapsed".

"I got to work two hours late, I got stuck in the middle of the Costanera [shopping centre] and from there I had to walk," she said.

Some people hitched lifts on the back of trucks.

Restaurants and cafes were among the businesses affected by the power cut.

Some remained open to offer those walking home a place to rest, but many closed because cash machines, card machines and fridges were not working.

Some of the most dramatic scenes unfolded in Fantasilandia, an amusement park in Santiago, where at least a dozen people were stuck on top of a rollercoaster.

Fantasilandia's manager said that while the park had backup generators, the attractions would not immediately restart for security reasons.

Hospitals relied on emergency generators for power.