An explosion ripped through a four-story residential building in central Madrid on Friday, injuring at least 17 people. Emergency services said they were searching for two missing people. Video released by the city of Madrid showed paramedics attending to the injured at the scene in the upmarket neighbourhood of Salamanca, as police and firefighters cordoned off streets cluttered with glass and debris. Four of the injured were taken to a hospital, including one person in serious condition after the blast sent plumes of smoke billowing over parts of the area. Emergency crews combed the building…