Ukraine suthorities are investigating a cyberattack as the possible cause of a power blackout in Kiev over the weekend that left many districts in the dark for several hours, UAWire reports, quoting a press release from the national power company Ukrenergo.

The outage occurred on the night of December 17, with electrical substation Pivnichna suddenly cut off from the main power grid.

“Hacker’s attack and equipment failure are among the possible causes for the power failures,” the power distributor said, adding that management of its automatic control systems will now be handled at a local level during the probe.

This blackout comes exactly a year after a cyberattack led to a blackout in western Ukraine, which Ukrainian authorities attributed to Russian hackers.

Read UAWire for more details.