(Bloomberg) -- A bus carrying a group of tourists crashed off a bridge near Venice late Tuesday killing at least 21 people, according to the regional governor.

Victims of the fatal accident included French, Croatian, German and Ukrainian citizens, as well as the Italian driver.

The bus, whose passengers included a group of visitors from Ukraine, caught fire after falling from the overpass near the Mestre railway station on the mainland across from Venice. Two children were among the dead. 

The passengers were returning to a campsite in the town of Marghera after visiting Venice, according to regional authorities. 

The driver may have suffered from the onset of a sudden health problem that led to the accident, regional Governor Luca Zaia said on Facebook. The bus broke through a guardrail before plummeting about ten meters, he said. 

The electric vehicle subsequently burst into flames for unknown reasons, the governor said, adding that surveillance video will be studied to determine the exact cause of the accident. At least 15 people were also injured in the crash, Zaia said.

Venice, which attracts millions of visitors from around the world, has seen a tourist boom in 2023, with about 2.5 million visitors in the first quarter of the year. The city recently approved a daily entrance fee in a bid to regulate the flow of tourists and to protect its ecosystem and cultural heritage. 

The scene of the accident is one of the main connections between the Italian mainland and the historic city built across more than 100 islands.  

“I am close to the families of the victims,” Prime Minister Giorgia Meloni said in a statement.  

--With assistance from Alberto Brambilla.

(Updates with regional governor in fifth paragraph.)

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