ROME –- A bomb exploded at the entrance of a high school in southern Italy, killing a 16-year-old girl and injuring at least four others as students were arriving at school for Saturday classes.

Police were investigating the likelihood of an organized-crime attack, but authorities said it was too early to exclude other possibilities.

At least one bomb was apparently attached to at least three gas canisters and placed in front of the high school in a suburb of the southern Adriatic port city of Brindisi. They blew up shortly before 8 a.m. News reports said they had been detonated remotely.

Reports initially said that it was almost certainly a Mafia-style attack in an area with a heavy presence of the Sacra Corona Unita, the Mafia outfit in Puglia, the heel of the Italian "boot."

But certain anomalies, such as the type of bomb and the choice of a school as a target, were leading authorities to pursue other hypotheses, reports said.

On Thursday, Italian authorities announced that they were increasing security for thousands of police outposts and offices considered potential targets of attacks triggered by anger over the country's economic crisis. The move came after a senior executive of a nuclear engineering company was shot in the leg May 7 by a gunman on a scooter in Genoa.

Interior Minister Anna Maria Cancellieri said on SkyItalia television that it was too early to favor any one theory over another in Saturday's bombing. But she added: "The method is not typical of Mafia attacks in the past."

She said the "very complex" attack was "an unprecedented act of cruelty."

A 16-year-old identified as Melissa Bassi died almost immediately after the explosion. A fellow student was in critical but stable condition following surgery. Others injured in the attack were treated for burns.

Nicola Torre, a senator from the Brinidisi area, said on Italian television that "this was a terrorist attack, in Mafia style, for the first time with the intent to kill our young people. It was set to kill the kids."

Authorities said that had the explosion occurred just minutes later it would have caused many more casualties among the mostly female student body at the fashion institute Morvillo-Falcone in the town of Mesagne.

The Sacra Corono Unita has in the past had a very strong presence in Mesagne, local commentators said.

They noted that the school is named after Francesca Morvillo, the wife of anti-Mafia judge Giovane Falcone, both of whom were killed in a huge explosion in Palermo. The 20-year anniversary of that attack is next Wednesday.

Also, the interior minister said that an extraordinary meeting of law enforcement and anti-Mafia specialists is set for Monday in Brindisi, a meeting she will attend.

And an anti-Mafia caravan that left Rome in April on its way to Palermo was scheduled to arrive in Brindisi on Saturday.

Piero Grasso, the special prosecutor that oversees Italy’s anti-Mafia efforts, was set to arrive on the scene later Saturday, reports said.

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-- Sarah Delaney

Photo: Police block off the site where a bomb went off outside Francesca Morvillo Falcone high school in Brindisi, Italy. Credit: Max Frigione / Associated Press

