Turkish Energy Ministry first claimed a major cyber attack, then the Minister investigated the issue in person:
As Mr. Albayrak, Minister of Energy, says in his Twitter account: He seriously warned those in charge about the ongoing problems.
Sonra BEDAŞ Genel Müdürlüğü'ne geçerek bu kez Avrupa Yakası'ndaki çalışmaları inceledik. Eksiklikler konusunda ciddi uyarılarda bulunduk. pic.twitter.com/f8ENLBIbQp
— Berat Albayrak (@BeratAlbayrak) December 31, 2016

Turkish Energy Ministry has been under a major cyber attack, Turkish media reported citing a senior source from the ministry. The report followed the major power outages in Istanbul that has been ongoing for three days