"A huge tragedy struck our community this evening," Mayor Luigi Brugnaro said on social media, saying "numerous victims" were on board. "An apocalyptic scene, there are no words."
Foreign tourists among the dead
Venice prefect Michele Di Bari — the local representative of the Interior Ministry — told Italian ANSA news agency that five Ukrainians and a German were among those dead.
Veneto region's governor, Luca Zaia, said victims reportedly included two children. "The victims and injured are of various nationalities, not just Italians," Zaia added.
"The operation to extract the bodies (from the wreckage) and identify them is ongoing," he said. The bus was also carrying passengers from France and Croatia, ANSA reported.
Venice official Renato Boraso said the bus was bringing tourists to a camping site.
The local health authorities activated the major emergency protocol, La Repubblica reported.
What do we know about the crash?
The bus veered off the road and fell close to railway lines in the district of Mestre, which is connected to Venice by a bridge. Images from the scene seemingly taken from the road above showed a bus lying upside down near a train line, still smoldering.
Officials said the vehicle fell around 15 meters (50 feet) onto electricity lines and caught fire at around 7:45 p.m. local time (1745 GMT).
The cause of the accident is unclear. Venice city councillor Renato Boraso said one line of investigation was into whether the driver of the bus, a 40-year-old Italian who was among those killed, had taken ill before the crash.
Italian Prime Minister Giorgia Meloni expressed her "profound condolences."
"I am in contact with mayor Luigi Brugnaro and [Transport Minister] Matteo Salvini in order to follow the news of this tragedy," she said in a statement.
rm, rmt, msh/jsi (AFP, AP, Reuters)