NAIROBI, Kenya (AP) — The longest nationwide power outage in Kenyans’ memory remained a mystery Sunday as the government-owned power company blamed a failure at Africa’s largest wind farm, which laid the responsibility on the power grid instead.

Some of Kenya’s more than 50 million people, including in the capital, Nairobi, saw power return almost 24 hours after the massive outage occurred late Friday. It was an embarrassment to the East African economic hub that has sought to promote itself as a tech center on the continent but remains challenged by alleged mismanagement and poor infrastructure.

Hundreds of people were stranded in darkness for hours at Kenya’s main international airport in Nairobi, leading to a rare public apology from a government minister in a country where tourism is a key part of the economy. “This situation WILL NOT happen again,” transport minister, Kipchumba Murkomen, said.

The head of the Kenya Airports Authority was fired after a generator serving the main international terminal had failed to start.

Shortly before midnight Saturday, Kenya Power offered the first detailed explanation of the outage, blaming it on a loss of power generation from the Lake Turkana Wind Power plant, Africa’s largest wind farm, causing an imbalance that “tripped all other main generation units and stations, leading to a total outage on the grid.”

But Lake Turkana Wind Power in a statement denied it was to blame. Instead, it said it had been forced to go offline by an “overvoltage situation in the national grid system which, to avoid extreme damage, causes the wind power plant to automatically switch off.” The plant had been producing nearly 15% of the national output at the time.

Such an interruption should be immediately compensated by other power generators in the system, the company said, but the continuing outages in the national grid were preventing the wind plant from being brought back online.

Kenya Power said it couldn’t even turn to importing power from neighboring Uganda, a relatively fast option that for some reason had been unavailable.

“We are jointly working on having the Uganda interconnector restored so as to enhance our grid recovery efforts,” it said.

President William Ruto, whose own office told The Associated Press on Saturday it was still running on generator power hours after Kenya Power announced it had restored electricity to “critical areas” of the capital, did not comment publicly on the crisis. Instead, he again criticized opposition calls for anti-government protests over the rising cost of living, calling them a threat to investors.

“Shame of a nation,” was the main headline of one of Kenya’s leading newspapers, the Sunday Nation. It said the outage was costing businesses millions of dollars and leaving some major hospitals to run on generators.

Kenya gets almost all its electricity from renewable sources, a fact that the government will promote as it hosts the first Africa Climate Summit early next month.