One person was killed and five were injured in an explosion in a residential block in the city of Antwerp, the Belgian news agency Belga reported on Thursday. Emergency services were continuing to search for other possible victims in difficult conditions, as the multi-storey building was rendered unstable by the blast, the cause of which was unclear. Two storeys are reported to have collapsed while people were inside. The victim was a 44-year-old man who lived in the house.