TRT World's Arabella Munro reports.
The death toll has risen to 37 and about 16 people are said to be seriously injured, while others remain missing under the crumbled debris.
He said the hypothesis for the collapse was a structural failure.
"There has not been sufficient maintenance and checks, and safety work for many bridges and viaducts and bridges in Italy constructed - nearly all - during the 1960s", he said.
Luigi D'Angelo, an official for the civil protection agency, said there were 30 cars and between five to 10 trucks on the road when the middle section came down. The Italian and the European Union flags will fly at half-staff on municipal buildings on Wednesday and Thursday, and residents are invited to express their condolences and support for the victims and their families, the mayor's office said.
Journalist Josephine McKenna brings latest from Rome.
"These kind of tragedies can not and should not happen in a civil country", Italy's transport minister, Danilo Toninelli, told the Italian TV channel TG1.
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It also indicated it would lend money at interest rates above prevailing market rates, an effective tightening of monetary policy. Last Friday , US President Donald Trump said he had authorised higher tariffs on aluminium and steel imports from Turkey .
"Autostrade per l'Italia's top management must resign", Transport Minister Danilo Toninelli said Wednesday in a post on Facebook.
"Autostrade per l'Italia was not able to fulfill its obligations under the contract regulating management of this infrastructure", he said on RAI 1 state television.
"I have given mandate to my ministry to start all proceedings to apply the agreement, that is to revoke the concession from these companies and seek significant sanctions which can reach up to 150 million euros based on the terms of the contract".
This technique also characterises another, even longer and just as problematic Morandi bridge: the 8.7-kilometre long General Rafael Urdaneta Bridge that spans the bay of Maracaibo, Venezuela, and was completed in 1962. Firefighters said that there are concerns about gas lines.
The technology of pre-stressed reinforced concrete used in the construction of the bridge was the hallmark of its designer, the celebrated Italian engineer Riccardo Morandi, who died in 1989.
Davida Di Giorgio shot the video on his cell phone which captured the moment of the collapse.
Vehicles on the bridge plummeted as far as 90 metres.
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Discussing the size of his squad recently, Sarri said: "I think the squad is too large, so I think some players have to go on loan".
Salvini said some 200 firefighters were responding to the accident.
"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 vehicle", Capello, who is now a firefighter, told TV news channel Sky TG24.
"I live nearby and I cross the bridge every day on foot", said Ibou Toure, 23, a translator.
Davide Capello, a former professional football player, was on a motorway bridge in Genoa in Italy when it collapsed. The motorway is a major artery to the Italian Riviera and to France's southern coast.
The motorway operator said work to shore up the bridge's foundation was being carried out at the time of the collapse, during which time it was being constantly monitored.
The A10 in Genoa is an important interchange between the northern regions of Lombardy and Piedmont and the beaches of Liguria, and to the main highway heading westward into France.
He said the shockwave sent him flying into a wall, injuring his right shoulder and hip.
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A war of sharp words also took place in January, when Turkey launched "Operation Olive Branch" against Kurdish fighters in Afrin. Erdogan also warned that Turkey could start looking for new allies if Washington damaged its relations with Ankara.
Rescuers scoured the wreckage of Italy's bridge collapse on Wednesday (Aug 15) as the death toll climbed to 38 and the government blamed the bridge's private owner, demanding resignations and moving to strip its toll concession.