Amid a widespread blackout, Spanish Prime Minister Pedro Sanchez on Monday, April 28, declared a state of emergency in the regions of Madrid, Andalusia, and Extremadura.

The decision, made at the request of regional authorities, allows the central government to coordinate the response efforts, including the deployment of military forces.

Sanchez also announced that a state of emergency would be declared in any other region that requested it. Later, Murcia, located in southeastern Spain, formally submitted a request, according to Spanish broadcaster RTVE.

"We do not know the causes. We are not ruling out any hypothesis,” Sanchez added in a speech to the nation.

Electricity went out across Spain and Portugal around midday and is being gradually restored. Many areas in Spain have endured nearly 9 hours without power.

While Sanchez said the security situation remained positive, much of Spain’s transport system ground to a halt. Metros and trains stopped service, while major cities experienced traffic gridlock after traffic lights failed.

Thousands of people also had to be rescued from elevators, with around 150 such incidents reported in Madrid alone, according to the capital city's mayor.

So far, Spanish media have reported some traffic accidents but no major looting or hits to critical infrastructure like hospitals, which are attending to emergencies.

Sanchez urged citizens to stay calm, conserve phone batteries, and avoid speculation or spreading misinformation about the causes of the blackout.

Train stations are remaining open overnight to allow stranded passengers to stay, according to Spanish daily El Pais, this is the worst power outage in Spanish history.

The blackout also caused widespread disruption in Portugal, whose prime minister said the issue originated from a problem in the Spanish system.