Both men were taken to hospital with burns on Wednesday evening and according to a bulletin from Region Östergötland, the older man had life-threatening injuries and his condition was critical.
The man was treated in the intensive care unit but died on Thursday.
Relatives are underprivileged.
The younger man's injuries were described as minor and he could be discharged on Thursday.
Investigated as a workplace accident
During Thursday morning, the police announced that the cause of the accident will be investigated.
The incident is classified as causing bodily harm through a workplace accident.
- We don't really know what has happened, but I hope we will get a little more clarity after our technicians have been on the scene today, says police investigator Anders Wallberg.