The fire, in the Alna area, left the cars completely destroyed, media including Dagbladet report.
Two cars initially caught fire before the blaze spread to a garage. The fire became so comprehensive that residents were asked by police to close their windows, Dagbladet writes.
Fire services put out the flames around 6:40am and the area had been secured by emergency services by 8am.
“The scene is currently still too warm for investigations (to begin),” operation leader Sven Christian Lie of Oslo Police District told Dagbladet.
There was no initial indication the fire was deliberately set, Lie also said.
“The investigation will give further clarification on this,” he said.
Surrounding roads were temporarily closed, affecting some bus routes, but these have since been re-opened, according to updates tweeted by Oslo Police.
Brannvesenet har slått ned det meste av flammene og det er noe mindre røyk. Tvetenveien er akkurat åpnet for trafikk.— OPS Politiet Oslo (@oslopolitiops) November 8, 2019
Buses were forced to queue at one point as the fire engulfed the garage at around 6:20am.
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