Three people were killed in an explosion at an apartment in downtown Copenhagen on Sunday, which police authorities suspect is a criminal act.Police and local emergency services were alerted to the explosion shortly after Sunday mid-day, where they found the three victims, including two men and one woman, in different parts of the apartment.According to Danish news agency Ritzau, the two men had sustained severe burns and were taken to Copenhagen University Hospital for treatment, but died of their injuries The woman is believed to have died shortly after the explosion.\"We suspect there may be a crime behind this. That is all I can say at this time,\" said Deputy Inspector Lau Thygesen of Copenhagen Police, in comments cited by Ritzau. Police confirmed that the three victims are related to each other. According to Danish broadcaster TV2, they are a 34-year-old woman, her husband, 38, and a 69-year-old man who was the father of one of the married couple.One of the dead men was a registered occupant of the apartment, which is located in the local council of Frederiksberg, in central Copenhagen, Ritzau added.The explosion was contained within the affected apartment, and no other properties or persons in the building were harmed, police said.