The lights are back on in Spain and Portugal. Nobody knows why they went out.

Portugal’s Prime Minister Luis Montenegro said Monday he did not know what caused the blackout but said “everything indicates” that it originated in neighboring Spain. His Spanish counterpart Prime Minister Pedro Sanchez said Monday he was also not sure what caused the problem.

“It is better not to speculate,” Sanchez said Monday.

Videos on social media and verified by NBC News showed residents of both countries cheering as power was slowly restored late Monday. People could be heard cheering and clapping in celebration in both Madrid and Barcelona as streets suddenly lit up.

Some might have preferred the blackout to go on for just a little longer.

Residents in Barcelona and Madrid poured to the streets amid the mayhem, taking the opportunity to disconnect, dance and enjoy picnic in the cities’ sun-drenched parks. Videos posted on TikTok documenting the relaxed atmosphere were given titles such as “digital detox” and “a good excuse to party.”

Even if they had tried, they may not have been able to get anywhere quickly.

Hundreds were stranded in elevators, with Madrid’s emergency management office saying Monday that it had conducted nearly 200 elevator rescues. Videos from the Spanish capital showed passengers walking to safety through darkened subway tunnels illuminated by emergency lights.

Traffic signals were rendered out-of-order forcing the Spanish Civil Guard police force to help coordinate traffic, which quickly clogged the city’s streets, and to help evacuate passengers from stalled trains.

Rail outages and disruptions to phone service left American tourists, Drew Toronto, 70, and Shelly Charnoff, 68, stranded when they tried to get back to Madrid following a tour of a cathedral in the nearby city of Toledo.

“No connection with anybody, and no access to any information in English about what was going on at the time,” Charnoff, told NBC News. The two eventually found a taxi to take them back to the city, he added.