South Africa’s largest city is used to dealing with national power outages that snarl traffic and cause delays due to operational issues at state-owned utility Eskom Holdings SOC Ltd.

Now Johannesburg’s electricity company has been targeted by hackers.

The attack didn’t affect the grid but denied access to City Power’s website and online power purchases Thursday.

Businesses and families in the nation’s commercial hub can be thankful for one thing: The lights are still on.