It was pretty much pitch black at first - I had the Sharapova match on - then all you could see for a bit was the lights from people's phones.
That must have been pretty scary for everyone. I was once in a supermarket when all the lights failed. Fortunately they got a backup system going very quickly which at least allowed shoppers to leave safely, after paying for their goods, of course. Me - I just dumped my basket and headed straight for the exit!