According to Bruno Cherchi, DNA tests could be utilized to verify the identity of some of the 21 people killed who were not carrying identification.
On Tuesday night, an electric bus crashed through a flyover barrier and fell about 15 meters (50 feet) in Mestre, which is connected to Venice by a bridge.
According to officials, among the dead were three children, including a newborn.
39 visitors were being transported by bus from the heart of Venice to a campsite.
Mayor of Venice Luigi Brugnaro described the incident as a "great tragedy." He said on social media, "Apocalyptic scene, there are no words."
Before falling off the highway, the car was seen speeding past another bus on the flyover's CCTV camera.
Except for a few adults, one rescuer described the situation as "a tragedy of young kids, if not very young people."
It is known that fifteen people—five of them seriously—have been hurt. Officials from Venice claimed that they also included tourists from Austria, Spain, Ukraine, and other countries.
The local governor reported that two 16-year-olds and two younger youngsters were among the injured.
Seven and thirteen-year-old German brothers were receiving medical care for damaged bones in a local hospital in Treviso. The accident claimed the lives of their parents, and the boys were receiving counseling.
Only three or four survivors had so far been allowed to speak with investigators, according to Venice prosecutor Mr. Cherchi, as of Wednesday afternoon.
On Tuesday, at about 19:45 (17:45 GMT), the bus crashed. It seems to have been chartered by a local business to transport tourists from the old part of Venice to a campground close in the Marghera neighborhood.
The prosecution continued, "Witnesses witnessed the bus scratching along the flyover guardrail for 50 meters before it fell to the ground.
In contrast to earlier reports that claimed the 13-tonne truck also used methane gas, the bus business emphasized that it was an electric vehicle. The bus's batteries caught fire, making the work of emptying the bus challenging, according to fire brigade captain Mauro Longo, who was speaking to the website Il Gazzettino.
Witnesses reported hearing screams, but the flames were too high for them to do anything.
The first individuals on the scene were a 27-year-old Gambian employee and a coworker. He described how he had removed three or four passengers, including a little girl, from the bus.
A man by the name of Leonardo claimed to have heard severe braking before the sound of the impact and to have hurried to the scene to investigate what had happened. He said on the La Presse website, "I wanted to help, but I was stopped by a friend of mine and a policewoman because the bus was still engulfed in flames and about to blow up."
Why the bus exited the flyover on a downward section of the road and careered through a metal barrier and a guard rail is still a mystery. Security camera footage from the area of the crash is being examined by police.
There was no evidence on the road that the bus company's 40-year-old driver, Alberto Rizzotto, who had been driving for seven years, had attempted to brake prior to the collision.
He stated that he was operating a "shuttle to Venice" in his most recent Facebook post.
According to the governor of the Veneto region, Luca Zaia, "everything pointed" to the bus driver becoming ill just before losing control of the vehicle. He did, however, emphasize that it was wise to refrain from speculating as to the accident's causes.
From the La Linea bus business, Massimo Fiorese, it was said that the bus was less than a year old and the driver had extensive experience.
He informed the Ansa news agency that a video of the bus moments before it crashed was available. "The car pulls up, slows down, and applies the brakes. It nearly comes to a complete stop before it crashes through the guardrail. I believe the driver became ill, as I am unable to account for it otherwise.
The bus collision was eventually removed from the scene early on Wednesday by firefighters.
In order to comfort the families of the victims, a reception area staffed by psychologists and psychiatrists has been set up at a neighboring hospital.
Giorgia Meloni, the prime minister of Italy, expressed the nation's condolences to the victims' loved ones and friends.
BBC