Authorities were called to a powerful blaze which broke out around 2am at a tanning salon in the centre of the Brunnsängs district.
Those who called in the fire reported having seen someone throw a fire bomb or similar object into the building followed by two people fleeing the area, according to police.
Residents in the area were evacuated, but the fire failed to spread beyond the tanning spa. By 3.30am, the fire had been extinguished and the area had been cordoned off for a technical investigation.
“It’s actually remarkable that it went so well, since it was really burning early on,” said Södertörn fire department spokesperson Henrik Nyman to the TT news agency.
Two hours earlier another fire had broken out at an Ica Maxi grocery store in the Södertälje’s Gensta district.
The fire started in two different parts of the building.
While the facility’s sprinkler system was triggered by the fire, the entire building suffered smoke damage, according to emergency services.