At least 21 people, including two children, were killed on Tuesday when a bus plunged off a bridge straddling a railway line in Venice, a city hall spokesman told reporters.
The crash caused "at least 20 deaths, including two children," the spokesman said.
Firefighters said the bus caught fire after careering off a bridge linking the Mestre and Marghera districts of the northern Italian city.
"A tragedy has struck our community this evening", mayor Luigi Brugnaro wrote on Facebook, describing the site of the crash as "an apocalyptic scene."
Italian Prime Minister Giorgia Meloni expressed her "profound condolences."
"I am in contact with mayor Luigi Brugnaro and (Transport) Matteo Salvini in order to follow the news of this tragedy," she said in a statement.