MILAN (CBS) — A bridge on a main highway linking Italy with France collapsed Tuesday in the Italian port city of Genoa during a sudden, violent storm, sending vehicles plunging almost 300 feet into a heap of rubble below. Genoa Mayor Marco Bucci told Italy’s Sky TG24 that more than 25 people were confirmed dead and 10 more rescued with injuries. Italian fire service officials told Italy’s ANSA news agency that at least 35 people had been killed.

Officials have warned that the death toll will likely rise further as the rescue and recovery effort continues.

Amalia Tedeschi, a firefighter, told RAI state TV that some 20 vehicles, including cars and trucks, had been involved in the collapse of a stretch of bridge some 260 yards in length. She said two people had been pulled alive from vehicles in the rubble, which fell into an industrial area below the bridge. Officials said they were being transported by helicopter to a hospital.

gettyimages 1016533884 At Least 35 Killed As Italian Highway Bridge Collapses

A picture taken on August 14, 2018 in Genoa shows a view of the Ponte Morandi motorway bridge, after one of its section collapsed injuring several people. – Rescuers scouring through the wreckage after part of a viaduct of the A10 freeway collapsed said there were “tens of victims”, while images from the scene showed an entire carriageway plunged on to railway lines below. (Photo by ANDREA LEONI/AFP/Getty Images)

French news agency AFP said it was a portion of the five-decade old Morandi highway bridge that collapsed. CBS News’ Anna Matranga reports there was maintenance work being performed on the bridge. Italian fire services said the bridge, in an industrial area in west Genoa, fell down at 5 a.m. Eastern time.

The private broadcaster Sky TG24 said a 200-yard section of the Morandi Bridge collapsed over an industrial zone, sending tons of twisted steel and concrete debris onto warehouses below. Firefighters told The Associated Press they were worried about gas lines exploding in the area from the collapse.

Photos published by ANSA on its website showed a huge gulf between two sections of the bridge. Deputy Minister Rixi said it was “the biggest tragedy involving a bridge of this importance in Europe in the last decades.”

Video captured the sound of a man screaming: “Oh God! Oh, God!” Other images showed a green truck that had stopped just short of the gaping hole in the bridge and the tires of a tractor trailer in the rubble.

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Rescuers are at work amid the rubble of a section of a giant motorway bridge that collapsed earlier, on August 14, 2018 in Genoa. – Rescuers scouring through the wreckage after part of a viaduct of the A10 freeway collapsed said there were “tens of victims”, while images from the scene showed an entire carriageway plunged on to railway lines below. (Photo by ANDREA LEONI / AFP) (Photo credit should read ANDREA LEONI/AFP/Getty Images)

ANSA said authorities suspected that a structural weakness had caused the collapse, but there was no immediate explanation by authorities for why they might have thought that or what had happened.

Italy’s transport minister, Danilo Toninelli, called the collapse “an enormous tragedy.”

The disaster occurred on a highway that connects Italy to France, and northern cities like Milan to the beaches of Liguria. It came on the eve of a major Italian summer holiday on Wednesday called Ferragosto, which means traffic was heavier than usual as Italians traveled to beaches or mountains.

The Morandi Bridge is a main thoroughfare connecting the A10 highway that goes toward France and the A7 highway that continues north toward Milan. Inaugurated in 1967, it is 295 feet high, just over half a mile long, with the longest section between supports measuring more than 200 yards.

It’s too early to say what caused the deadly collapse of a highway bridge in the Italian city of Genoa, but corrosion or weather conditions could have been part of the cause, a structural engineer specializing in bridges told the Associated Press.

“As this reinforced and prestressed concrete bridge has been there for 50 years it is possible that corrosion of tendons or reinforcement may be a contributory factor,” said Ian Firth, former president of The Institution of Structural Engineers.

“The fact that there was reported to be a storm at the time may or may not be particularly relevant. In addition, ongoing work on the bridge may or may not be partly responsible for the collapse,” he added.

gettyimages 1016573546 At Least 35 Killed As Italian Highway Bridge Collapses

A destroyed truck is pictured as rescuers are at work amid rubble and wreckage after a section of a giant motorway bridge collapsed earlier in Genoa on August 14, 2018. – At least 22 people were killed on August 14 when the giant motorway bridge collapsed, with several more feared dead in what Italy’s transport minister described as an “immense tragedy”. The collapse, which saw a vast stretch of the A10 freeway tumble on to railway lines in the northern port city, was the deadliest bridge failure in Italy for years, and the country’s deputy transport minister warned the death toll could climb further. (Photo by ANDREA LEONI / AFP) (Photo credit should read ANDREA LEONI/AFP/Getty Images)