The bang, hard to place but described roughly as a deep sound similar to an earthquake, was heard shortly after 3.30pm east of the capital city centre, particularly in the Saltsjö-Duvnäs, Nacka and Lidingö areas.
Similarly loud noises were also reported earlier in the day out in the Stockholm archipelago.
However, it later emerged that the bang had probably been caused by an aircraft breaking the sound barrier. Swedish fighter jet manufacturer Saab said it had been carrying out test flights throughout the day.
“We have carried out planned test flights with Gripen E. It was quite far out at sea, but it could be heard from a distance if the wind is blowing in a certain direction,” spokesperson Johan Öberg told the TT newswire.
The Swedish National Seismic Network, based at Uppsala University, confirmed that there had not been any earthquake activity in the Stockholm area, and agreed that the bang was likely caused by the aircraft.
A test flight of a Saab Gripen E on a separate occasion. Photo: Linus Svensson/Saab