Police on Tuesday seized street fighting weapons and petrol bombs. Thirteen addresses in Mälärdalen and Stockholm were raided by the police.
A raid on one address, believed to be in Eskilstuna, provided plenty of criminal evidence, according to the police.
Sörmland's police spokesman Frederick Wallen , said the evidence involved street fighting weapons and petrol bombs. He also confirmed that the crackdown is linked to a criminal investigation into the left extreme network Revolutionary Front.
"Through the raid we have been able to prevent a planned arson attack," said Fredrik Wallen to SVT Sörmland.
Johanna von Wovern , spokesman for police in Västmanland , told SVT that the dawn raid "Eskil" was linked to two investigations. One of them is an investigation by Västmanland police concerning vandalism, assault and two counts of aggravated assault in Kolsva September 29, 2012.
Other arrests Tuesday, were according to Johanna von Wowern in connection to an investigation into a serious assault in central Stockholm on 14 September this year.