The fire started in the cellar on Observatoriegatan in Vasastan, in the centre of the capital, when two workers were trying to cut away a gas pipe. The pair were among the three people injured. The identity of the third person is so far unclear.
“The gas appears to have been pressurized, which caused it to catch fire, injuring two people, Sven Mählqvist at Stockholm Fire Brigade told news agency TT.
Around 20 firefighters were called in to put out the blaze and traffic was diverted from the scene. The fire was extinguished within half an hour, police spokesman Björn Engström said, but Observatoriegatan remains closed.