Blackouts across Taiwan trapped people in elevators after a fault at a coal- and gas-fired electricity plant before power was eventually restored.
Taiwan suffered a day of rolling blackouts traced to a power plant near southern Kaohsiung City on Thursday.
Citizens were urged to "remain calm" amid rolling outages before power was restored around 8 p.m. local time (12:00 UTC).
Taiwan President Tsai Ing-wen apologized and promised an investigation.
Reports emerged of people trapped in elevators, mostly in the north of Taiwan, said fire service officials.
State-run Taiwan Power said the trigger was a substation fault at the coal- and gas-fired Hsinta Power Plant near the southern city, which sources coal shipped mainly from Australia and Indonesia.
Thursday's blackouts, affecting at least 6 million homes, were run in rotation to ration remaining capacity across Taiwan's electricity grid, said the utility.
The Economy Ministry said the main airport in the capital, Taipei, was operating normally.
Quick repairs were vital for Taiwan's key semiconductor exporters.
Taiwan Semiconductor Manufacturing Co (TSMC) said its power had been restored after a "brief power dip." Other semiconductor firms in Hsinchu, Tainan and Taichung, also said they were not impacted.
Taiwan's blackouts came in a nation already unsettled by rare, new domestic coronavirus cases, despite tight border controls and viral tracing begun last year that had kept it largely coronavirus-free.
A government briefing to reporters in Taipei on that situation was also disrupted by Thursday's outage.
Taipei Mayor Ko Wen-je, in a social media post, urged residents: "Please don't panic… Taiwan has abundant medical capabilities."
Sixteen new domestic viral cases reported on Wednesday represented a record daily high for Taiwan. They were traced, said the government, to outbreaks at an airport hotel and among pilots of Taiwan's largest carrier, China Airlines Ltd.
ipj/rt (dpa, Reuters, AP)