Italian Prime Minister Giuseppe Conte declared Wednesday a 12-month state of emergency in Genoa following the collapse of a motorway bridge that killed at least 39 people.

"A cabinet meeting took place in which we have decreed a 12-month state of emergency and made available a first allocation worth five million euros ($5.7 million) for the national emergencies fund," Conte said in a press conference in the northwestern port city after the meeting, which lasted around an hour.

Conte also confirmed the government's intention to revoke the contract from private sector firm Autostrade per l'Italia, which was in charge of operating and maintaining the bridge and the A10 motorway it was part of.

Transport Minister Danilo Toninelli and Deputy Prime Ministers Luigi Di Maio and Matteo Salvini announced the move earlier on Wednesday.

Toninelli's ministry confirmed to AFP that the A10 contract was the only one currently being looked at.

"This is a tragedy that is unacceptable in a modern society, and this government will do everything in its power to prevent anything of this kind from reoccurring. We have already announced that we will begin the process of revoking the Autostrade concession," Conte said

A vast span of the Morandi bridge caved in during a heavy rainstorm in the northern port city on Tuesday, sending about 35 cars and several trucks plunging 45 meters (150 feet) onto the railway tracks below.

At least 39 people are known to have died and 15 injured, according to Italy's Civil Protection service.

Children aged eight, 12 and 13 were among the dead, Interior Minister Matteo Salvini said on Wednesday, adding that more people were still missing.

Three Chileans, who live in Italy, and three French nationals were also killed, according to their respective diplomatic services.

Hundreds of rescuers continued their search on Wednesday after scouring the huge piles of concrete and twisted metal overnight by floodlight, hoping to find survivors.

The bridge forms part of a motorway that is operated by Autostrade, a unit of Milan-listed Atlantia group. Earlier, the company said it had carried out regular, sophisticated checks on the structure before the disaster and that these had not shown up early signs of trouble.

Italy's government said it intended to revoke the company's contract and hit it with a fine of 150 million euros ($170 million).

Deputy prime minister Luigi Di Maio, who arrived in Genoa on Wednesday morning, earlier said the tragedy "could have been avoided."

"Autostrade should have done maintenance and didn't do it," he said.

Aerial footage of the viaduct shows lines of abandoned vehicles stretching across the remaining section of the bridge, with one truck perched towards the edge of a gaping precipice where a huge part is missing.

Fire official Emanuele Gissi, who told AFP that three bodies were retrieved during the night, said two large cranes were set to be used in the rescue and recovery operation, which is expected to take days.

"All accessible spaces have been explored, now we are moving the largest pieces of debris," Gissi said.

"We cannot know if there are survivors remaining, but it's our job to search."

More than 200 meters (650 feet) of the 1960s bridge crumpled without warning as traffic crossed the busy stretch of motorway on Tuesday, in the deadliest disaster of its kind in Europe since 2001.

The collapse came as the bridge was undergoing maintenance work while the Liguria region, where Genoa is situated, experienced torrential rainfall.

Italian President Sergio Mattarella said a "catastrophe" had hit Genoa and the whole of Italy.

"Italians have the right to modern and efficient infrastructure that accompanies them safely through their everyday lives," Mattarella said.

'I went down with the car'

Genoa's leading public prosecutor Francesco Cozzi on Wednesday said that the incident "definitely wasn't bad luck."

"We need to respond to just one question: Why did this happen?"

Some that plunged down with the bridge managed to escape unscathed, including a former goalkeeper for Italian Serie A club Cagliari.

"I was driving along the bridge, and at a certain point I saw the road in front of me collapse, and I went down with the car," Davide Capello told TV news channel Sky TG24.

The incident is the latest in a string of bridge collapses in Italy, a country prone to damage from seismic activity but where infrastructure generally is showing the effects of a faltering economy.

Pope Francis also sent his condolences to the victims, saying the tragedy has "caused desperation among the population," at a service for the feast of the Assumption.

'A tragedy waiting to happen'

Genoa, home to half a million people, is located between the sea and the mountains of northwestern Italy.

Its rugged terrain means that motorways that run through the city and the surrounding area are characterized by long viaducts and tunnels.

The Morandi viaduct, completed in 1967, spans dozens of railway lines as well as an industrial zone with several factories.

It has been riddled with structural problems since its construction, which has led to expensive maintenance and severe criticism from engineering experts.

On Tuesday specialist engineering website "Ingegneri.info" published a piece that highlighted how the bridge had always presented "structural doubts", calling it "a tragedy waiting to happen".

One factory, immediately next to one of the viaduct's support columns, was virtually empty on Tuesday on the eve of a national holiday, and seems to have sustained minimal damage.

"I live nearby and I cross the bridge every day on foot," said Ibou Toure, 23, a translator. "I was never sure of it, you'd always hear these noises whenever lorries were going over.

"When I heard it had collapsed, I wasn't surprised."

Genoa is a flood-prone city, and officials were warning that the debris from the collapse must be removed as soon as possible. Some of the wreckage landed in a dry riverbed that could flood when the rainy season resumes in a few weeks.

'It could have happened to anyone'

Residents of Genoa, one of Italy's biggest port cities, are in shock over the collapse of a busy bridge that served as a motorway bypass.

"I always crossed the bridge, for everything, to see my family, to go to work", 22-year-old Dario told dpa. "Everyone from Genoa crossed the bridge. It could have happened to anyone," he added.

Italian media published pictures of a green supermarket van that stopped just before the abyss where the 200-meter-long section of the bridge had stood.

"At one point everything shook," was the account of the van driver, as reported by the Corriere della Sera daily. "The car in front of me disappeared, it seemed like it had been eaten by the clouds."

"I looked up, I saw the bridge pillar collapse. I braked. I did not just brake, I slammed on the brakes" and "when I saw the void ahead of me, I reversed, trying to escape from that hell," he added.

According to Corriere della Sera, Genoa resident Andrea Rescin was the first to call the emergency services, after seeing the collapse from the balcony of his apartment.

"It looked like a bomb, the first thing that came to my mind was an explosion," he was quoted as saying. Corriere said the emergency services did not believe him at first.