The mayor of Milan has compared a fire that ripped through a 20-storey residential building on Sunday to the Grenfell Tower blaze in London that killed 72 people four years ago. The fire, which started on the upper floors of the tower on the southern outskirts of the capital of the Lombardy region, spread to the rest of the building owing to what experts described as the “chimney effect”, which turned the building into a torch. According to the authorities, about 20 residents suffered slight smoke inhalation. Dozens of ambulances and fire engines were at the scene. The building houses about 70 families, who were being contacted in an effort to make sure no one was missing. All the residents who were in their apartments when the fire broke out – about 30 people – were safely evacuated. Officials said the flames had spread through the cladding on the facade, which was supposed to have been fire-resistant, Corriere della Sera reported. Milan’s mayor, Beppe Sala, wrote on Facebook: “What was clear from the start was that the building’s outer shell went up in flames far too quickly, in a manner reminiscent of the Grenfell Tower fire in London a few years ago. “The tower was built just over 10 years ago and it is unacceptable that such a modern building should have proved totally vulnerable.” Angelo Lucchini, a professor of technical architecture at the Polytechnic University of Milan, told Corriere della Sera: “The facade of the building was built with combustible materials. Unfortunately there is no law that prohibits it.” One resident told La Repubblica: “We had invested everything for that apartment. Everything we had went up in smoke. We have nothing left.” Prosecutors in Milan have launched an investigation to determine the cause of the fire. According to Carlo Sibilia, an interior ministry official in Rome, “the rapid spread of the flames was due to the thermal covering of the building”. Authorities now fear the building is at risk of collapse, owing to the high temperatures that could have melted the steel columns. The deaths in the Grenfell Tower fire were blamed on exterior cladding panels made of flammable material. Owners of flats in similar buildings across Britain have since been forced to remove such panels at a cost estimated to run into billions of pounds, forcing many residents into economic hardship. The 60-metre-high building in Milan was designed to look like the keel of a ship. It included an aluminuim sail on its roof, which burned after the blaze, falling in pieces to the street.