It was shortly after three on Wednesday morning that a witness saw two people steal the catalyst.
- He tried to prevent the thieves from leaving the place but was then run over on foot and may also have been beaten, says Björn Öberg, the police's spokesperson.
Police sent several patrols to the area but have not yet been able to find the suspects.
The man who was injured was himself called for an ambulance and according to the police, he did not appear to have received serious injuries.
A report of assault and theft is being prepared.