VENICE, Italy (AP) — Venetians stopped in dismay Wednesday to pay respects to the 21 foreign tourists who were killed when an all-electric shuttle bus crashed through an overpass guardrail and fence, plunging more than 10 meters to the ground.

It’s a road they had traveled many times and considered safe but now stopped to inspect the aging guardrail and rusted fence.

The bus, which was just a year old, crashed to the ground and landed upside down on Tuesday night. The 40-year-old driver was among those killed and 15 people were injured.

The driver, who had an untarnished record, had just started his shift shuttling tourists from Piazzale Roma, at the edge of Venice’s famed canals, to a four-star campground on the mainland offering bargain accommodation.

A video shows the city-owned bus disappear from the frame, as another larger bus traveling behind it continued along the elevated road. Prosecutors said the shuttle bus scraped against the guardrail for at least 50 meters (yards) before its fiery crash to a surface road opposite the Venetian borough of Mestre’s train station.

The guardrail was bent to the pavement; the fence ripped open and the front of the bus completely crushed.

Italian firefighters work at the scene of a passenger bus accident in Mestre, near Venice, Italy, Wednesday, Oct. 4, 2023. According to local media, the bus fell a few meters from an elevated road before crashing Tuesday close to Mestre’s railway tracks, where it caught fire. (Antonio Calanni/AP Photo)

“Inexplicable,’’ said Mayor Luigi Brugnaro, who added that he had driven on the overpass hundreds of times. Regional Gov. Luca Zaia said the circumstances suggested the driver may have been suddenly taken ill.

Investigators hope that video from the scene will reveal the dynamic of what happened.

Five Ukrainians and one German were among those killed. The Italian driver who was identified as Alberto Rizzotto. Two of the dead were children. The rest of those who perished have yet to be identified.

The injured included at least four Ukrainians, part of a larger group that included a 3-year-old girl who suffered serious burns, as well as visitors from Spain, Austria, France, Croatia and Germany. Nine were being treated in intensive care for trauma, including burns and fractures. Survivors included a young Austrian brother and sister.

“They are still in what we call the shock phase, with confused memories, they are still in that state of agitation and confusion typical of the traumatic event,” said Rita Lorio, a psychologist at Mestre’s main hospital, one of five treating the injured. ”They are not yet in that phase of awareness of what happened.”

The tourists are all believed to have stayed at the Hu Venezia Camping in Town, just a 15 minute drive from the shuttle bus’s pickup point at Piazzale Roma, at the edge of Venice’s famed canals linked to the mainland by a bridge.

The crash has shocked Venetians, two-thirds of whom live on the mainland. Many stopped on Wednesday morning to pay their respects, staring at the gaping guardrail and fence. One man stopped on his motorcycle to tie plastic flowers to a post.

Family members of the dead and survivors were trickling in to Venice from around Europe on Wednesday. The Veneto region declared three days of mourning, and flags were flown at half-staff at government business.

Experts said the fact that the bus was electric contributed to the massive fire and made rescue operations more difficult.

“I won’t forget what I saw for the rest of my life,” Brugnaro, the mayor, told The Associated Press from his office in Mestre. “Seeing all those people crammed inside a bus, down there, is something you can’t describe.

Venice is in the process of replacing its buses with electric vehicles. They have been introduced on the city’s Lido island several years ago, with a small percentage added to the fleet in Mestre last year.

Brugnaro said the accident did not give him reason to pause the city’s plan to upgrade city transport to less-polluting electric buses, even if it needs to be determined what role the battery might have played in the ensuing blaze.

The bus drove off the overpass, he said. “It has nothing to do with the fact that it is electric.”

Gianni Amadeo, an 80-year-old retired musician, stopped in disbelief Wednesday at the site that he passes regularly between his home and a garage he uses for storage.

“It took a scary flight,” he said of the bus’s plunge before continuing on his way.

Godstime Erheneden was in his apartment overlooking the busy road when he heard a crash and rushed outside. He was among the first to enter the bus.

“When we went in, we saw the driver right away. He was dead. I carried a woman out on my shoulders, then a man,” Erheneden told the local newspaper il Gazzettino.

“The woman was screaming, ‘my daughter, my daughter,’ and I went back in. I saw this girl who must have been 2 years old. I have a son who is a year and 10 months old, and they are the same size. I felt like I was holding my son in my arms. It was terrible. I don’t know if she survived. I thought she was alive but when the rescuers arrived, they took her away immediately,” Erheneden said.

Brugnaro said he had read what Erhenden and his roommate did. Both were identified as long-time residents of Italy who work for the Fincantieri shipbuilding company. The mayor said he planned to track them down once the emergency phase had passed.

“They threw themselves into the fire to rescue these people. They are real heroes of our time,” he said.

Zampano reported from Rome. Associated Press writers Ciarán Giles in Madrid and Sylvie Corbet in Paris contributed to this story.