On August 14, 2003, at approximately 4:05 pm EDT, people across North America lost power for up to two days.
The blackout hit most of Ontario and the eastern seaboard and was the second largest blackout of its time, after the 1999 Southern Brazil blackout.
Around 50 million people were left without power, along with 100 power plants, which included 22 nuclear plants.
It all began when a high-voltage power line in northern Ohio grazed against several overgrown trees and shut down. Typically, the problem would have tripped an alarm, but the alarm system failed leaving millions in the dark.
The failure triggered a blackout in Ontario, which impacted about 10 million people.
Traffic lights began blinking in the height of rush hour, as brave Samaritans jumped in the middle of the roads in an attempt to redirect traffic. In Toronto, subway systems came to a screeching halt in the tunnels.
Thousands of commuters were left shoulder-to-shoulder in complete darkness, stranded and sweating underground. People were panicked and confused as to what was happening. Citizens were forced to either stay downtown or walk several kilometres home in the painfully hot, humid weather, which soared to the high 30s.
Toronto officials asked residents to withold from unnecessary use of water, as pumps were not working and there was only a 24 hour supply. Non-essential workers were also asked to stay home the next day.
Stores quickly ran out of batteries and emergency supplies as residents stocked up on anything they could find.
No one had any idea how long the blackout would last. For some, it lasted until 11 pm, EDT, for many others, it was not until 8 am the next day.
The event contributed to at least 11 deaths and cost an estimated $6 billion according to reports.
All of southern Ontario was affected except Niagara Falls and Fort Erie. Some areas to the north were also impacted including, Attawapiskat and Moosonee and west to Marathon.
Following a three month investigation, officials concluded that the blackout was a result of human error and equipment failure.