The explosion occurred just after midnight Saturday. The van, a municipal maintenance vehicle, was completed destroyed.
As of Sunday, the 26 year-old man injured in the blast was in intensive care at Oulu University Hospital and unable to tell police anything about the incident.
Police evacuated the vicinity because of the danger of explosion from a number of remaining oxygen and acetylene canisters. Emergency services announced that the danger had passed at around 3:30 AM.