No fewer than 21 people were killed while others injured, five in critical condition, after a bus ran off a flyover near the Italian city of Venice before bursting into flames on Tuesday.

The incident happened at 7:45 pm (local time) when the bus, reportedly a rental vehicle to shuttle tourists between Venice and a campsite in the nearby Marghera district, broke the barrier and plunged into railway tracks connected to Venice by a bridge.

According to the BBC, the petrol-powered bus went up in flames after falling on power lines. Five Ukrainians, one German and an Italian driver, were among those killed in the crash.

Luigi Brugnaro, Venice mayor, called the incident a “huge tragedy” and “an apocalyptic scene, in which there are no words,” he said on social media, as officials warned the death toll could rise.

“Our thoughts go out to the victims and their family and friends,” Prime Minister Giorgia Meloni said in a statement.

European Union Commission president Ursula von der Leyen said she is standing by Italian leaders in this “moment of profound pain.”