At least 21 people, including two children and foreign tourists, were killed and several others injured when a methane-powered bus crashed off a bridge in Venice and caught fire.

"A tragedy has struck our community this evening," Mayor Luigi Brugnaro said on Facebook, calling the crash site "an apocalyptic scene."

PHOTO | COURTESY bus accident kills dozens in Italy

"The preliminary toll is at least 21 deaths and over 20 hospitalisations," stated Luca Zaia, governor of the Venice area, lamenting a "tragedy of enormous proportions."

"Efforts are on to extract and identify the bodies," he stated. "The victims and the wounded include people of several nationalities, not just Italians."

According to a city hall source, the dead included Ukrainian visitors, while the Italian news agency ANSA reported that the victims included German and French citizens.

A local official told AFP that the injured were three Ukrainians, Croatians, German, and French nationals.

The tragedy happened around 7:30 p.m. local time when the bus returned from Venice's historic quarter to a camping spot.

PHOTO | COURTESY bus accident kills dozens in Italy

According to firefighters, the bus caught fire after crashing off a bridge that spans a railway line and connects the Mestre and Marghera districts of the northern Italian city.

According to an AFP photographer, fire workers were busy working on the burned remnants of the truck, which was overturned on its top.

Firefighters waited for the vehicle's battery to cool before moving it to look for more victims. Italian Prime Minister Giorgia Meloni conveyed her "heartfelt sympathies."