Many Sydneysiders could be arriving home to darkness tonight.
Ausgrid emergency crews are on their way to restore power to around 8,000 homes and businesses in Sydney's north-west
The power was interrupted just before 5pm.
The affected suburbs include Cherrybrook, Beecroft, Pennant Hills and surrounding areas.
At this stage, emergency crews from Ausgrid are hoping to have the power back on by 930pm, but that will depend on the extent of damage to the equipment, so that time could change.
"Crews are inspecting equipment at a substation in Pennant Hills," says Ausgrid spokesperson Phillipa Wheeler
"They're investigating whether there was a lightning strike nearby, but they're working as quickly as they can to get the power back," she said.
"The network will have to be rerouted around the damage in order to restore power."
The outage is also affecting traffic lights in the area.
Ausgrid has apologised to customers and thanked them for their patience tonight.
Check the latest Ausgrid outages here.