At least 21 people are dead and 12 are injured after a bus plunged from an overpass above a railway line between the Venice districts of Mestre and Marghera on Tuesday, the local prefect's office said .
Four or five people are unaccounted for, officials said.
The bus burst into flames after falling around 10 metres from the overpass.
Premier Giorgia Meloni expressed her "most profound condolences" and said she was thinking of the victims and their families and friends.
Police sources said that two children were among the victims and Veneto Governor Luca Zaia confirmed that minors were involved in the disaster.
"The victims and injured are of various nationalities, not just Italians," Zaia said in a social-media post.
"The operation to extract the bodies (from the wreckage) and identify them is ongoing". (ANSA).