alt Hacker NewsLook up Air Busan Flight 391, a power bank in someone's carryon caused the entire plane to burn down in 5 minutes. The airplane (an Airbus A321) was destroyed. The only reason there was not total loss of life was because the plane hadn't taken off yet.
This could happen with any battery-powered device though. But I don't see ICAO or FAA banning e.g. laptops any time soon, even though they may carry more energy than a single power bank.