CLEVELAND (WJW) — It was 20 years ago Monday that a major power outage left millions across the midwest and northeast in total darkness.

In Northeast Ohio, things were at a standstill for many hours during the Blackout of 2003.

But could it happen again?

It was just after 4 p.m. on Aug. 14, 2003: the largest blackout in U.S. history knocked out power to 50 million people in eight states and parts of Canada. The outage forced hundreds of thousands of workers in Northeast Ohio, from doctors and police officers to restaurant staff and retail, to make their way home with no traffic lights or clear direction.

Cleveland’s water supply was cut off, and SkyFox surveyed the surreal scene over downtown Cleveland at nightfall, many living in fear, not knowing how long the outage would last.

Matt Brakey, president of Brakey Energy, which provides comprehensive energy management services to large users of energy in Ohio, said it “absolutely could happen again.”

He said with the cause of the 2003 blackout being a combination of generator malfunction at FirstEnergy’s power plant in Eastlake, a software glitch and sagging transmission lines coming into contact with trees, it could very well happen again.

“If at any time there is more or less electricity being consumed and demanded, the electric grid can be out of balance, and you start to experience the types of failures that we saw on that fateful day,” he said.

Full power was restored within 48 hours, a scary scene in history that many will never forget.