Spain and Portugal declared a state of emergency after an all-encompassing power failure struck those nations as well as Belgium, Andorra and France.

The Spanish power distributor calls it “exceptional and extraordinary.” Power went down just after noon and by nightfall only half of the power had been restored in Spain. The cause was not immediately clear Monday.

Hours after a massive power cut hit large parts of Spain and Portugal, Spanish PM Pedro Sánchez says the cause is still being investigated