Two girls die and several students injured in bomb blast in Brindisi

STORY HIGHLIGHTS
NEW: Two girls die and several other students are injured by the blast, Brindisi mayor says
NEW: "There were school back packs and notebooks everywhere," an official says
The device exploded in front of the vocational school as students arrived
It is not yet clear who is responsible or why the school was targeted
Rome (CNN) -- Two 16-year-old girls have died and several are injured following an explosion outside a school in the southern Italian city of Brindisi, its mayor said Saturday.

Brindisi Mayor Mimmo Consales told CNN one of the girls died in surgery from the injuries she sustained in the blast.

One of the injured is in a serious condition, he said.

Fabiano Amati, regional minister for Italy's Civil Protection agency, said the scene shortly after the blast was "dramatic."

"There were school back packs and notebooks everywhere. Many windows of the nearby buildings were broken," he told CNN.

Amati said the police had found three gas cylinders at the site that were detonated with a remote control.

The device was concealed behind a trash can by a wall 50 meters from the entrance of the school, he said.

"It's an attack on all Italians because schools are considered a secure area," Amati said. "It's the first time in our country that a school is under attack."

The explosion occurred early Saturday as students were arriving at the school, which offers vocational training, Italy's ANSA news agency reported.

It is not yet clear why the school was targeted or who carried out the attack.

Police chief Francesco Cirillo told CNN that the motive for the bomb is under investigation and that no one has claimed responsibility.

Nichi Vendola, governor of the Puglia region where Brindisi is situated, said: "It could be either a mafia or a political terrorism attack. It's too early to say. It's an unprecedent event."

The Francesca Morvillo Falcone school is named after the wife of a prominent anti-mafia judge, which has fueled speculation that the organized crime group might be behind it. Falcone was assassinated in Palermo, Sicily, in 1992.

The school is located near both the tribunal and the city's tax collection agency.

Italy's tax collection agencies, called Equitalia, have been targeted by mail bombs, Molotov cocktails and suicides in front of their offices in recent months, with the incident s occurring in the cities of Rome, Livorno and Bologna, respectively.

The local anti-racket commission of Mesagne, a town in Brindisi province, issued a warning last week of heightened threats by both organized crime groups and anarchists against government agencies.

An anti-mafia march that scheduled for Sunday will go ahead as scheduled.

CNN's Joseph Netto and journalists Livia Borghese and Barbie Nadeau contributed to this report.