A nationwide power cut hit Ethiopia overnight after a technical fault at a massive hydroelectric dam.
Power cuts are common in Ethiopia, but rarely on such a big scale.
The dam has caused controversy in Ethiopia and has been blamed for cutting the water supply to northern Kenya, causing Lake Turkana to shrink.
Ethiopia is currently building an even bigger dam on the River Nile, which has led to a diplomatic spat with Egypt and Sudan.
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State media says the power went out when a circuit breaker tripped at Gibe III dam in southern Ethiopia and engineers have now rectified the problem.
But BBC Ethiopia correspondent Emmanuel Igunza says that many areas across the country still do not have electricity.
Gibe III is Ethiopia’s main source of power and was described as Africa’s biggest dam when it was built in 2016.
Ethiopia is currently building the bigger Grand Renaissance Dam along the River Nile. It will cost $4bn (£2.9bn).
But the project is opposed by Egypt, which says the dam threatens the water supply to downstream countries.
Talks to solve the dispute between Ethiopia, Egypt and Sudan have stalled.