A ransomware infection at an electricity provider in the city of Johannesburg, South Africa’s biggest city and financial capital, has left some of its residents without power. The ransomware infection impacted City Power — a provider of pre-paid electric power for Johannesburg residents and local companies. The infection, which took root yesterday, is now preventing customers from buying electrical power units, or feeding (selling) electrical power back into the grid, which some residents are producing from solar panels.

On Twitter, there have been quite a few Power City customers who complained over the last 12 hours about blackouts at their homes and across the city, and not being able to buy new electricity.

City Power is owned by the City of Johannesburg. The company also said the ransomware has made it more difficult to respond to outages at the same speeds as in the past, due to a lack of access to internal applications.

The company said it was increasing the number of support teams it was keeping on standby, in case of an emergency.