If a looming helium shortage isn’t enough to dissuade you from getting balloons for your next birthday party, consider the consequences if they escape from their ribbon moorings and end up brushing against some high-voltage power lines. You might be safer decorating for your kid’s party with hand grenades.

This incident was filmed in Long Beach, California, and the explosion is likely the result of the balloons being made from shiny mylar, a metallic polyester film that conducts electricity, in this case creating a devastating short circuit. The resulting explosion knocked out power for hours in the neighborhood, and the balloons were never seen again.

[YouTube via Geekologie]