Italy was in shock yesterday after a 16-year-old girl died, and five other teens were gravely injured in a bomb blast at a school, as investigators cast doubt on possible involvement by the mafia.

I was opening the window and the blast wave hit me.I saw kids on the ground. All blackened. Their books on fire

There were scenes of chaos and carnage when the powerful blast went off at the entrance of the building just as students were arriving for morning classes at the vocational high school in Brindisi in mafia-heavy southern Italy.

“I was opening the window and the blast wave hit me. I saw kids on the ground. All blackened. Their books on fire. It was terrifying,” an employee at the prosecutor’s office next to the school told the Repubblica daily.

Another teenage student who witnessed the blast told local television: “I had just gone into the bar in front of the school. I saw everything falling.”

A middle-aged woman, still under shock, said: “I saw a girl lying on the ground and another one who got up and started shouting: ‘Melissa! Melissa!’”

The victim, Melissa Bassi, suffered horrific injuries in the blast and was taken to hospital but died a short while later.

“Melissa, an only child, meant everything to herparents,” said Mesagne mayor Franco Scoditti after having visited the family. “Her parents literally lived for their daughter.”

The explosive was composed of three gas canisters with a timer device hidden in a container next to a wall just outside the school, Italian media reported.

Debris could be seen scattered over a wide area at the scene of the blast.

Hospital official Paola Ciannamea said that one of the injured girls, who is also 16, was in a “very serious condition” with injuries to her chest.

The four other victims being treated are all suffering from extensive burns and five more have been discharged from hospital with lighter injuries. The blast went off at around 7.45 a.m. Most Italian schoolchildren and students attend classes on Saturday.

Students at the school, which teaches social work, tourism and fashion, were due to hold a fashion show later in the day.

The bomb caused shockwaves across Italy, with Prime Minister Mario Monti ordering flags flown at half-mast for three days. The government called it “an extremely grave and atrocious criminal act”.

The president of neighbouring France, Francois Hollande, expressed his country’s “deep solidarity” with Italy in the face of this “odious attack”.

The Vatican called it a “an absolutely horrific and vile act”.

Local regional governor Nichi Vendola said: “This is a horrific attack that feels like sacrilege. We must act firmly and with determination.”

No one has claimed responsibility for the blast and Interior Minister Anna Maria Cancellieri said investigators were looking into “numerous hypotheses”.

Local chief prosecutor Cataldo Motta said it wouldbe illogical for the mafia tobe behind the bombing asit seeks support from thepopulation.

“Local mafia organisations want social consensus. This act would go against their interests because it would alienate any sympathy,” Motta said.

The perpetrator “might not be a mafia organisation,” he added.

Italian media pointed out that the school is named after the wife of famous anti-mafia judge Giovanni Falcone, who was assassinated with her husband and three bodyguards in a bomb attack by the mafia 20 years ago last Wednesday.

Asked about the coincidence, Motta said: “Too many coincidences could be just that. We have to ask ourselves who benefits. In general, there are claims of responsibility for terrorist attacks. We have received none.”

Brindisi mayor Mimmo Consales also cast doubt on a mafia link saying: “Frankly the device, the methods used do not correspond to organised crime.”

Local civil society groups including anti-mafia campaigners organised a large demonstration in the city later on yesterday in a gesture of solidarity.

The Sacra Corona Unità, the local mafia in the Apulia region, is involved in drug smuggling and human trafficking.

The group has been targeted by numerous police raids in recent years and its influence is believed to be on the wane.