The rescue service received an alarm about smoke from a garage in Märsta just after 02 o'clock.
-It is a garage above ground on two levels, it is estimated that at least a hundred cars are on fire, says Magnus Bengtsson, commanding officer at Räddningscentral Mitt, to TT at 03 o'clock.
The risk of spreading is difficult to estimate.
Eight fire trucks were on site at 03:00 and the extinguishing work will take several hours.
-It's like a blast furnace, it's burning full.
You try to put it out as best you can from the outside.
You can not get close, it is simply too hot, says Magnus Bengtsson.
Heavy smoke development
The smoke development is strong and the smoke blows over a residential area nearby.
-All smoke is dangerous, and there are a hundred cars burning so it is clear that the smoke is unhealthy.
Those who live nearby must close doors, windows and ventilation, says Magnus Bengtsson.
No injuries have been reported.