Venice authorities declared three days of mourning Wednesday after a bus crash killed 21 people including a toddler, sparking debate over the state of Italy's crumbling infrastructure.
Fifteen people remain in hospital following Tuesday evening's crash, officials said, at least five of them in a serious condition.
Road safety campaigners that this was an accident waiting to happen, because of a lack of investment in road safety equipment.
The bus broke through a guardrail on an overpass, landing upside down next to a railway line below and catching fire.
"The bus flipped upside down," said Mauro Luongo, Venice's fire brigade commander. "The impact was terrible because it fell from over 10 metres (32 feet)."
Emergency workers spent hours removing bodies from the charred, crushed wreckage. Investigators were still trying to identify the dead Wednesday. They have turned to DNA samples to confirm their identities, as the bus was carrying around 40 tourists from Venice's historic centre to a camping site, and many passengers did not have documents.
Venice Mayor Luigi Brugnaro described the accident site as "an apocalyptic scene". He declared three days of mourning, with flags on official buildings to be flown at half-mast and books of condolences opened for well-wishers.
- 'All young' -
Boubacar Toure, a 27-year-old from Gambia who had been working at a building site near the accident, told journalists he had been called over by the fire brigade to help with the rescue.
"I pulled three or four people out, including a little girl, and also a dog. The driver was already dead," Toure said.
Officials confirmed the death toll was 21, including a one-year-old child and a teenager.
The victims include five Ukrainians, a German, and the Italian driver, Venice Prefect Michele di Bari told journalists.
Ukraine's foreign ministry told AFP, however, that four of its citizens were among the dead.
The injured include four Ukrainians, a German, a Croatian, and two Spaniards, di Bari said.
Doctor Federica Stella said the injured passengers transported to the nearby hospital in Mestre were "all young" and all foreign.
Family members were "arriving little by little" from their home countries, she told AFP.
- 'Tragedy foretold' -
Firefighters said the bus fell from an overpass straddling a railway line and linking the mainland Mestre and Marghera districts of Venice in northern Italy.
Footage from a roadside camera, passed to journalists by local sources, showed it travelling in the far-right lane.
Another bus obscures it from view for a few seconds before it is seen again, toppling slowly off the overpass.
"The main hypothesis at the moment is that the bus driver... may have fallen ill," said the president of the Veneto region, Luca Zaia.
But Domenico Musicco, head of an association for road accident victims, said it was "a tragedy foretold".
"The guardrail was designed for a country road, whereas here we needed new-generation equipment that could have prevented the bus from falling," he told AFP.
"Italian road maintenance is poor. Too little is invested in road safety. It is estimated that 30 percent of accidents are down to that," he said.
Massimo Fiorese, director of the company that was operating the bus that crashed, told ANSA news agency the bus had only been put into service last year and was in perfect condition.
Italian Prime Minister Giorgia Meloni had earlier expressed her "profound condolences", while several European leaders also sent messages of support.
In July 2018, a bus carrying a group of some 50 holidaymakers back to Naples fell off a viaduct near the city killing 40 people in all.
