The section of the bridge which fell to the ground in its entirety can be seen clearly in the clip recorded by an aircraft circling overhead.
At least 22 people were killed in the collapse, according to the country’s transport minister, Danilo Toninelli.
“I’m following with great apprehension what has happened in Genoa, which appears to be an immense tragedy,” Mr Toninelli said in a statement posted on social media.
Structural weaknesses may have caused the disaster, Italy’s ANSA news agency reported authorities as having said.
Sited near the port city of Genoa, the bridge was built for the A10 motorway in the 1960s, with restructuring work reportedly carried out in 2016.
According to reports in Italian media, the collapse took place near an industrial zone, raising fears about gas pipes potentially exploding from the knock-on effects of the disaster.
The country’s interior minister Matteo Salvini said around 200 firefighters had responded to the accident and that the government was “following the situation minute-by-minute”.
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