A power outage left thousands of Tulsa residents in the dark early Friday.
Power has come back on in most areas.
Many people reported hearing a loud boom just before the outage.
The failure of a piece of equipment at the substation at 81st and Garnett caused the outage.
The piece of equipment that failed is called a lightning arrestor. It is designed to protect other pieces of equipment from lightning strikes.
Power outages were around 81st and Garnett where the initial failure took place. The outage reached into Broken Arrow as well.
PSO reports over 13,000 customers were without power at one point.