Rocio Vilaplana, a dentist in southeastern Spain, was closing a suture in a patient’s mouth during oral surgery early Monday afternoon when the lights went out.
“Everything started beeping,” Ms. Vilaplana said.
Her backup generator kicked in, the emergency lights in her surgery room flickered on and the 36-year-old dentist tried to remain calm. “Let’s just close it properly,” she thought to herself.
Dr. Vilaplana finished the delicate procedure, but it would be the beginning of a day of frayed nerves and widespread confusion across Spain and Portugal, as a daylong power outage brought life to a standstill for tens of millions. People spent the night in train stations huddled under blankets, stuck in their apartments without water or working elevators, staring at their suddenly useless cellphones and wondering what had happened.
On Tuesday, with electricity almost entirely restored in the two countries — though the cause of the outage remained under investigation — many people reflected on the anxiety of being left not only without power, but also without cellphone service, internet access or the ability to pay for anything except with cash.
In Murcia, a city in southeastern Spain, the word on many residents’ lips on Tuesday morning was “locura” — insanity.
“The worst was the lack of communication,” said María José Egea, 71, who spent a nervous evening in her seventh-floor apartment, the elevator out of service. Neighbors came to check in on her, she said, although good information was scarce and rumors about the cause of the blackout flew.
“People were coming and telling me nonsense,” she said. “Everyone had a theory. ”
In the Spanish capital, Madrid, residents in the Arganzuela neighborhood filtered into the streets on Monday, confused by what was happening. Some stared at their unconnected phones. Others gathered outside health centers, shops and bars to try to gather information.
A small crowd collected at an auto repair shop on Martín de Vargas Street, where the owner, Fernando Palacio, opened the doors of a car he was working on and played a news broadcast on the radio — the only reliable source of information throughout the day.
It reminded Mr. Palacio of a 1981 coup attempt in Spain, he said Tuesday morning, with “everyone glued to the radio.”
Naturally, people flocked to the stores that were still open to buy batteries, cooking charcoal, toilet paper and other essentials. By nightfall, some store shelves in cities like Murcia were empty.
“We were actually quite scared,” said María Cantero, 41, a restaurant server in Archena, about 15 miles outside Murcia. She made a run to the store to buy formula for her 5-month-old daughter and candles. As night fell and the power was still out, she felt uneasy.
In Peniche, Portugal, about 60 miles north of Lisbon, José Boto, a 69-year-old pensioner, had a tough day.
He was standing in line at a supermarket, holding a chicken — his lunch — when he was told there had been a power outage and that payment could only be made in cash. “I had to leave the chicken behind,” he said.
By Tuesday morning, life was regaining its rhythms. Ms. Cantero drove her daughter, Lucía, to a doctor’s appointment in Murcia. The traffic lights were working again, and the police officers who had deployed to intersections to direct traffic a day earlier were gone.
The Spanish capital was not quite back to its bustling self. Many residents appeared to be staying home. Schools were open, although few were holding regular classes.
María del Carmen Sánchez, a caretaker at Cervantes Secondary School in the Lavapiés neighborhood of Madrid, said that “barely 5 percent of the students” showed up on Tuesday.
Still, she said, despite “the chaos of the situation, I think everything went quite well. People were very patient, although there were some nerves and concern at first.”
For others, the disruptions of the previous day lingered.
Anthony Saas, 24, a student from Zgharta, Lebanon, was stranded in the southern Spanish city of Córdoba on Monday after his train home to Jaén, where he is studying, was canceled. He spent a sleepless night at the train station, covered by a Red Cross blanket, and he was still there on Tuesday morning, holding a plastic bag with his belongings and waiting for his rescheduled train home to be announced.
“It was a tough night,” Mr. Saas said. It was his first visit to Córdoba, he added, “and I don’t even know if I will ever come back.”
As the authorities continued to search for the cause of the blackout, many across the region prepared for several days of digging out.
At her dental clinic in Murcia, Dr. Vilaplana donned her scrubs and mask again on Tuesday morning. She was planning to work up to 13 hours to try to fit in all of her canceled patients and attend to new emergencies.
For the next few days, she said, “it’s going to be completely crazy.”
Samuel Granados contributed reporting from Córdoba, Spain. Tiago Carrasco contributed reporting from Peniche, Portugal.
