BRINDISI, Italy — Italy was in shock on Saturday after an unexplained bombing at a school killed a 16-year-old girl and left five other teens gravely injured, sparking emotional protests across the country. There were scenes of chaos and carnage when the powerful blast went off at 7:45 am (0545 GMT) near the entrance to the building as students were arriving for classes at the vocational high school in the southern city of Brindisi. "There was huge black smoke, debris all over the place, piercing screams," Corradino De Paolis, a passer-by who rushed to the scene, told AFP. Debris including charred notebooks at the site of the blast was spread over a wide area as investigators combed the area in search of evidence. Victim Melissa Bassi's friend, Veronica Capodieci, also 16, was in a "very serious condition" with injuries to her chest, hospital doctors said. The four other victims being treated were all suffering from extensive burns and five more had been discharged from hospital with lighter injuries. No one has claimed responsibility for the blast and Interior Minister Anna Maria Cancellieri said investigators were looking into "numerous hypotheses." The explosive was composed of three gas canisters with a timer device hidden in a container next to a wall just outside the school, which teaches social work, tourism and fashion and is named in honour of a victim of the mafia. The region where the attack took place is a hub of the Sacra Corona Unita (United Sacred Crown), a ...