Spanish power grid operator Red Eléctrica said on Monday it was working with energy companies to restore power after a major outage struck large parts of Spain and Portugal.

Spanish radio stations reported that parts of the Madrid underground were being evacuated, while traffic jams clogged the city centre as traffic lights failed, according to Cadena SER.

E-Redes, a Spanish electricity grid monitoring company, said it was working to re-establish connections in phases.

Spain’s Prime Minister and Energy Minister are en route to Red Eléctrica’s headquarters to monitor the situation, Cadena SER reported.