Things that go bump in the night

In the early hours of Saturday morning, I awoke to what sounded like a loud explosion, followed by a noise a little like breaking glass. I turned on the light and went to investigate. Possibilities ran through my mind. It sounded a bit like a car bomb a few streets away, but that seemed unlikely. More plausible was the idea that an electric substation had overloaded and some glass insulating conductors had fallen from melted cables.