At least 21 people died and more than a dozen others were injured on Tuesday night when a coach powered by methane smashed through the guard rail of an overpass near Venice and plunged 50ft to the ground, bursting into flames.
The mayor of Venice described the scene of the crash as “apocalyptic”.
The horrific accident happened on a stretch of road between the towns of Mestre and Marghera, which lie across the lagoon from Venice on the mainland.
The bus, which had been rented by a group of tourists, was returning from Venice’s historic centre to a camping site when the accident occurred around 7.30pm local time (6.30pm BST).
At least two children were believed to be among the victims. Around 18 people were reported to have survived the crash.
The victims reportedly included five Ukrainians, a German and the driver of the vehicle, an Italian.
Matteo Piantedosi, the interior minister, said: “The aggravating factor was methane and the fire spread rapidly. I fear that the death toll will rise.”
It was not known why the bus veered off the overpass and smashed through the safety barrier, but Mauro Luongo, the fire brigade commander of Venice, said the impact of the crash caused the vehicle’s electric batteries to catch fire.
The driver, named as 40-year-old Alberto Rizzotto, was among the dead.
Giorgia Meloni, the prime minister, expressed her “most profound condolences” and said her thoughts were with the victims and their families and friends.
“Mamma mia, a coach just fell from the bridge,” a woman could be heard saying on video footage that was uploaded to social media. “Mamma mia, mamma mia, look at this,” she said.
The footage showed the vehicle in flames and passersby rushing to help survivors.
“I heard a loud braking sound, I thought it might have been a train,” said one witness, named Leonardo.
“Then there was the noise of the crash, the impact. I was shocked and looking down I saw smoke and heard people screaming for help.”
He rushed to the scene of the accident. “I wanted to help but I was stopped by a friend of mine and a policewoman because the bus was still on fire and there was the risk of an explosion. The rescuers arrived after about 20 minutes.”
“The victims and injured are of various nationalities, not just Italians,” said Luca Zaia, the governor of the Veneto region, which encompasses Venice.
“The provisional toll is at least 21 fatalities and over 20 people hospitalised,” he said, deploring a “tragedy of enormous proportions”.
“The operation to extract the bodies (from the wreckage) and identify them is ongoing.”
Luigi Brugnaro, Venice’s mayor, wrote on Facebook: “A tragedy has struck our community this evening, I’m speechless”, describing the site of the crash as “an apocalyptic scene”.
“There are at least 20 dead, but some people are still trapped in the wreckage,” he later told Italian state television channel Rai News24.
Firefighters said the bus caught fire after swerving off a bridge and plunging about 100ft onto railway tracks below. They used ladders tried to access the burned-out interior of the vehicle as black smoke billowed from its windows.
There have been a number of deadly bus crashes in Italy in recent years.
In 2017, 16 people on board a bus carrying Hungarian students died in an accident near the northern city of Verona, while in 2013, 40 people died when a bus plunged off a viaduct in southern Italy in one of the country’s worst road accidents.