Kenya and Uganda were plunged into darkness on Tuesday evening after large parts of the two neighbouring countries experienced power outage.
Utility firms in the two nations said they were working to address the problem.
"We are aware of the wide area outage affecting many areas. Our teams are currently working with @uetcl[the power producer]to establish the cause, resolve it and restore supply ASAP. Kindly bear with us," Umeme Limited, Uganda's electricity supplier, said in a tweet.
"A power system disturbance has led to loss of electricity supply to some parts of Nairobi and adjacent areas," Kenya Power said in a statement, adding that "engineers are battling to identify the fault and restore power supply as quickly as possible."