A Senegalese man abducted 51 children when he hijacked an Italian school bus and set the vehicle alight in a protest over migrant deaths in the Mediterranean.

Ousseynou Sy, originally Senegalese but with Italian citizenship, stopped the bus he was driving, with two classes of high school students on board.

He was said to have ordered the children's hands to be bound and threatened to kill them and himself during the drive, before setting the vehicle on fire when he was stopped by a police blockade today.

Officers broke the glass in the back door of the bus and got all the passengers to safety without serious injury before the flames destroyed the vehicle, authorities said.

As he was apprehended, the driver said he was protesting migrant deaths in the Mediterranean, Commander Luca De Marchis told Sky TG24.

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The remains of the bus in San Donato Milanese, near Milan, which was set alight this morning

Firefighters and police officers attended the scene after a student aboard called the police

The incident happened in San Donato Milanese, a town near Milan, Italy.

The 47-year-old father of two, whose ex-wife is Italian, has been arrested and charged with carnage and kidnapping, worsened by the fact that most of the people involved are under age.

De Marchis told Sky TG24 that the driver, an Italian citizen of Senegalese origin in his 40s, threatened the passengers, telling them that 'no one would survive today' as he commandeered the bus carrying two middle-school classes in Cremona province, some 25 miles (40 kilometres) from Milan.

ANSA quoted one of the students as saying the driver took all their phones and ordered the chaperones to bind the students' hands with cable ties, threatening to spill gas and set the bus ablaze.

The student, whose name was not given, said a classmate managed to conceal his phone.

Authorities said that an adult called an emergency operator, while one of the students called a parent, and they alerted authorities, who set up roadblocks.

The 47-year-old driver set the bus alight and then he threatened to kill himself, saying deaths in the Mediterranean must be stopped

The bus was intercepted on the outskirts of Milan by three Carabinieri vehicles, which were able to force it into the guardrail, De Marchis said.

'While two officers kept the driver busy - he took a lighter and threatened to set fire to the vehicle with a gasoline canister on board - the others forced open the back door,' De Marchis said. While the evacuation was underway, the driver started the blaze.

De Marchis credited the officers' 'swiftness and courage,' for getting out all the children and their teachers 'with no tragic consequences.'

Some of the passengers were treated at a hospital, mostly for cuts and scratches related to the evacuation and firefighters also attended the scene, he said.

The driver was apprehended and was being treated for burns, while Italian media reported 12 students were rushed to hospital.

ANSA identified him as Ousseynou Sy, and said he was being investigated on suspicion of kidnapping, intention to commit mass murder, arson and resisting law enforcement.

De Marchis said he had previous convictions, but did not specify their nature.

ANSA reported that Sy, who became an Italian citizen in 2004, had been convicted in 2007 and 2011 of drunken driving and sexual molestation of a minor.

Massimo Traetta, who was driving in the opposite lane, witnessed and filmed the scene

Policemen were called by a student after the driver started screaming, showing a can of gasoline and a lighter

Sky TG24 said that the driver had worked for the bus company for 15 years without any employment-related issues.

'Investigators must clarify how the transport company permitted such a delinquent ... to drive a bus, especially one carrying children,' said Riccardo De Corato, a Milan provincial official for security.

Video showed firefighters dousing the bus that had been completely gutted by flames, leaving only the charred metal frame.

Massimo Traetta, who was driving in the opposite lane, witnessed and filmed the scene, showing the children running away from the bus after the police arrived to attend the incident.

The Italian newspaper La Repubblica reports that, before setting light to the bus, the man shouted: 'I want to be done, deaths in the Mediterranean must be stopped.'

Sy, who has been an Italian citizen since 2004, has a criminal record for driving in a state of drunkenness and for a case of sexual abuse on a minor, the Italian newspaper reported.

According to early reconstructions of the incident, the man had to bring the two student classes from the high school Vailati di Crema to the gym, but he diverted the route.

Officers broke the rear windows of the bus, letting the children get off while the man set the bus on fire

A student reported that Sy wanted to head towards the airport.

Witness aboard the bus said Sy started screaming while driving, showing a can of gasoline and a lighter.

One of the students aboard called the police who arrived quickly and stopped the bus near the junction with Peschiera Borromeo, Milan.

Officers broke the rear windows, letting the young students get off the bus while Sy set it alight.

Another student aboard the bus told Repubblica: 'He was threatening us, saying if we moved he would have poured the gasoline and set a fire.

'He kept saying that people in Africa die and it is the fault of Di Maio and Salvini.

'Then the police saved us.'

Autoguidovie, a society managing the school bus service, said: 'The man, our coworker since at least 2002, has been working full time since 2004.

'Over the years he has never shown any signs of mental imbalance, neither have we ever received any complaint regarding his behaviour as a driver.

'As a company, we did not know anything about his criminal record.'

An investigation at the driver's house is ongoing.

Investigators also asked four of the students who were aboard the bus to go back to where the accident took place to reconstruct what happened.