Around 50,000 households lost power in southern Stockholm on Thursday morning, with the areas Södermalm and Hägersten-Liljeholmen the worst hit, said energy provider Ellevio.
Swedish radio reported based on information on Ellevio's website that as many as 80,000 households were without power at 9am, but according to Ellevio the outage never affected as many as that.
“Some areas may have been registered twice,” said spokesperson Thomas Kult.
Ellevio said power had been restored everywhere by 10am.
The blackout also affected public transport, with trains grinding to a halt on the metro's red line between Liljeholmen, Norsborg and Fruängen, and the green line between Fridhemsplan and Alvik.
Trains were running again by 9.30am, but with knock-on delays.
It was not immediately known what caused the power cut.