A commission of European experts will investigate the causes of the incident occurred Friday afternoon in the European power transmission system and which left several areas in northwestern Romania without electricity, sources from the Energy Ministry told Agerpres news agency.

“No one so far knows what the incident’s causes are. A European commission has been set up to find out the circumstances of the incident,” the sources said.

“This is an interconnection system breakdown. We don’t know the exact causes yet, but we will analyze them. It is a zonal problem in the northwest of the country. The power supply has been meanwhile entirely restored,” officials of the national electricity transmission company Transelectrica said.

“An incident that occurred on Friday at 15:05 in the interconnected European electric transmission grid caused equipment in Romania’s electric transmission grid and in other countries to go off. The northwestern part of Romania was affected. Romania’s electric transmission grid was restored to normal operating parameters around 16:00, the power supply was restored to all affected consumers around 16:45,” the company’s release reads.

The European Network of Transmission System Operators (ENTSO-E) announced that the synchronous area of Continental Europe was split into two separated grid regions for an hour in the afternoon of January 8, and that an area in the south east region of the interconnected grid was separated from the rest of Continental Europe during that period. A temporary frequency drop of approximately 250 mHz was also registered.

“Coordinated actions and an immediate response taken by the Continental European Transmission System Operators ensured that the system stability was not affected in most European countries,” ENTSO-E said.

The European association adds that an investigation is ongoing on the cause of this system split and further information on this incident will be made in due course.