No-one was reported injured after the incident in the Vällingby suburb, but the building's facade and window panes were badly damaged.
"We've visited the affected apartments and haven't found any injured people. Nor are there any reports that any of those who were working at the site were injured," Eva Nilsson, press spokesperson at Stockholm police, told the TT newswire.
Police were unable to share details of what happened at the site, other than confirming that a planned explosion went wrong at around 2pm on Wednesday.
The company responsible for the building work has launched its own internal investigation and the area was cordoned off on Wednesday afternoon. Police have classified the incident as endangering others and work environment crime, according to SVT Nyheter.
The construction site is next to an apartment block with 48 homes, of which a total of six were reported damaged by the blast. Tenants who were not able to stay in their homes had been evacuated to hotels, and will be relocated to temporary accommodation today, SVT reported.