Dozens of big cities and provinces across Turkey have been hit by a massive power outage, the government has not ruled out an outside attack on the system.
The massive power cut caused chaos across the country, with metro and tram services in Istanbul, Ankara and three other major cities being brought to a standstill. Services and businesses without back up power supplies were also disrupted.
The Turkish Electricity Transmission Company (TEIAS), said a problem with the country's power transmission network was the cause of the outage.
When asked if the outage may be the cause of a terror attack, Prime Minister Ahmet Davutoglu said "all possibilities are being investigated."
Energy Minister Taner Yildiz, said "was there an operational fault, a technical fault, or was there a cyber attack?...we are following it closely."
Live flight tracking website, Flightrader24, reported 11 of Istanbul airport's 16 air traffic towers have been affected by the power outage with some aeroplanes being diverted.
News channel CNN Turk reported 30 of Turkey's 81 provinces have been affected.
Yildiz said a crisis center had been established for those affected.
jlw/lw (AFP, AP)