"Safety is our top priority and the cause of this incident is being investigated. We apologise to customers for the inconvenience caused by the power cut and our staff restored all supplies as quickly and safely as possible."
More top news
The unlicensed events unfolded on Saturday night at Clapham Common and Tooting Bec Common.
A 37 year old man who was taken to hospital after getting into difficulty in a stretch of water near Maidenhead has died.
Jonty Bravery, who is mentally ill, has been jailed for 15 years after throwing a six year old boy from the Tate modern balcony.