Ramy Shehata, of Egyptian origin, secretly rang his father on a hidden mobile phone after the driver demanded the children hand their phones over.
Italy’s Ansa news agency reported that the 13-year-old made the call while pretending to pray in Arabic, but he was actually issuing a warning to his father who then phoned the police.
After police arrived, the driver allegedly doused the vehicle with a flammable liquid and shouted: “No one will survive today.”
The bus, which had been transporting two classes of schoolchildren from the province of Cremona to Milan, went up in flames.
But police managed to rescue all of the passengers through broken windows before the fire destroyed the vehicle, and there were no serious injuries.
Ramy’s father, Khaled Shehata, who immigrated from Egypt in 2001, told Ansa news agency his son was born in Italy in 2005 but was never issued official citizenship documentation.
“My son did his duty, it would be nice if he got Italian citizenship now,” he said.
”We would love to stay in this country. When I saw him yesterday I hugged him hard.”
Government officials said on Thursday they would fast-track and pay for the boy’s citizenship application.
“The interior ministry is ready to take care of the expense and to fast-track citizenship for this little hero,” officials said in a statement.
Currently, children born to immigrant parents in Italy have to wait until they turn 18 before being eligible to apply for citizenship.
Meanwhile, the interior minister Matteo Salvini said he hoped to be able to revoke the Italian citizenship of the alleged bus driver under a security decree that the government introduced in December.
Ousseynou Sy, a 47-year-old Senegalese immigrant who became an Italian citizen in 2004, has been charged with attempted murder, kidnapping, resisting arrest and arson.
Prosecutors said there were no indications that Mr Sy was radicalised or had ties to Islamic terrorists, but that he claimed the kidnapping was to draw attention to refugee deaths in the Mediterranean Sea.
Mr Sy allegedly bought a canister of petrol and restraints a day before the attack on Wednesday.
He also sent a video to friends in Italy and Senegal indicating plans for bold action, with the message “Africa, Rise up”, prosecutors said.
Mr Sy has previously been convicted in 2007 and 2011 of drunken driving and sexual molestation of a minor, prosecutors added.
Sky TG24 said the driver had worked for the bus company for 15 years without any employment-related issues.
Since coming into power in June, Italy’s ruling right-wing League party and populist Five Star Movement have established a strong anti-immigration stance.
The country has previously threatened to close its ports to humanitarian refugee rescue ships.
Last year, nearly 2,300 migrants and refugees died while attempting to cross the Mediterranean Sea to reach Europe, according to the UN.
Additional reporting by Associated Press