“Rome is the only capital in the world where you see a bus in flames in the city center,” the paper’s editorial read, “a 10-meter-high smoke chain, people running away, explosion, police and firefighters’ sirens, and nobody thinks of ISIS, but ATAC.”

It was no accident that my first inquiry after the explosion was to ATAC, rather than the police.

“ATAC immediately opened an internal investigation to ascertain the cause of the fire that developed on board,” a company statement said, repeating much of the conversation I had with a spokesman.

“The fire didn’t cause any consequences to the passengers,” it added. “The vehicle was completely destroyed.”

The city offered no explanation, and officials could not be reached for comment.

The cause, however, is self-evident: The buses are too old and almost certainly too little serviced. The two buses that burst into flames on Tuesday were built in 2003 and in 2004. On average, public buses should be in service for six to seven years, not 15, transportation experts say.

“Old buses simply break more easily and even finding components to replace becomes a challenge,” said Gabriele Grea, a professor of economics and management of local public transportation at Bocconi University in Milan. “These kinds of fires are rare, but generally depend on the poor maintenance of antiquated vehicles.”

After years of little funds and scarce attention, the center-left national government kicked off an ambitious plan last year to renovate the public transportation fleet across the country. Yet the process takes time and Rome finds itself in an especially awkward position.

ATAC, the company for bus and rail transport in the city of Rome, has a national reputation for passengers who fail to buy tickets — and jump off as soon as ticket collectors, who are rarely spotted, come on board. Drivers, many of whom have little problem multitasking on their cellphones, are not asked to check tickets. The company’s employee absence rate is well beyond the national average.