"It's a full-blown fire," says Anders Sessler, regional response leader at Södertörn Fire Brigade Association.
No people or animals are reported to have been harmed.
"It was a herd of animals that was released from the barn," says Anders Sessler.
All train traffic stopped
The fire has spread and, according to the emergency services, 4000 square meters are burning.
Since the fire is heavy and the railway is nearby, all train traffic passing the section between Södertälje and Järna has been stopped.
There is currently no forecast for when the fire may be extinguished.
– There are four stations in place plus drones and helicopters from MSB are on their way, we are doing what we can, says Anders Sessler.