Imagine taking the subway to work when the train comes to a sudden halt halfway between scheduled stops. You pull out your smartphone to go online and see what the problem is, but you have no reception – no cell signal, no internet. 

Hours later, rescue workers arrive to extract you and your fellow passengers from the stalled train. You make your way to the street in hopes of taking a taxi or an Uber. But without your phone apps and with credit card machines inoperable, you are forced to search for an ATM – only to discover those aren’t working, either.

You soon realize that everyone else is in the same predicament. Hospitals operating on emergency backup systems. People trapped inside elevators. Traffic snarled due to inoperable stoplights. Gas station pumps not functioning. Airport terminals closed. People in darkened homes desperately searching for candles and battery-operated radios to learn what’s happening. 

On April 28, the residents of Spain, Portugal and parts of France didn’t have to try to imagine this nightmare scenario. They found themselves prisoners of it for hours when an unprecedented blackout impacted at least 55 million people after the Iberian Peninsula electric grid system failed. 

The outage, described as one of the worst ever in Europe, “disrupted businesses, hospitals, transit systems, cellular networks and other critical infrastructure,” according to the France 24 news channel.