About ten firefighters are working on site with the extinguishing work.
They were helped to find the fire by firefighters, as it was in the woods.
The difficult-to-access location also makes it unclear how large an area it is.
There are no buildings in the area and thus no danger to human health and life, but internal commander Mikael Kalered is worried that the fire will spread quickly if they do not manage to extinguish it soon.
Therefore, firefighting aircraft have been called in to water bomb.
- It's terribly dry.
I hope that there will be a fire ban this weekend because there can be major consequences of a fire, he says.
On Tuesday, SMHI issued a warning about the risk of forest fires in southern Sörmland, as well as an announcement about high temperatures on Wednesday morning.
The latter is not formally a warning, but may become so if the temperature rises further.