During the night, it burned in a total of six different places in Trollhättan.
Between 22.26 and 22.32 on Thursday evening, the first four alarms were received.
Later that night, it burned in two more places.
The police suspect a connection between the first five fires and have now initiated a preliminary investigation into aggravated arson and damage by fire.
- If there are several or a single perpetrator, I dare not speculate, says Göran Carlbom, duty officer at the police.
The fires have, according to the police, occurred within a short period of time in scattered but close places.
No people are currently said to have been injured.
"Get car fires in response"
SVT's reporter Richard Veldre is on site at the parking garage that burned during the night.
The post-extinguishing work is still ongoing on Friday morning and the smoke continues to spread in the area.
- The police have started a feverish activity.
You have an idea of what this might be about.
It has happened before that you have started an effort and that you then get car fires in response.
It is something you look at now as well, if there is a connection with previous police interventions, says Richard Veldre in Morgonstudion.
Similar fires have occurred earlier in Trollhättan.
But the difference now compared to then is, according to Richard Veldre, the geographical spread.
- That it is in so many places at the same time, I have not been with as long as I have worked here, he says.
No suspected perpetrators are said to have been arrested so far.