Excavators have begun clearing large sections of the collapsed highway bridge in the Italian city of Genoa in the search for people still missing three days after the deadly accident.

The search entered a new phase on Friday as heavy equipment removed a large vertical section, clearing a new area to probe.

Rescuers have been tunnelling through tons of steel, concrete and crushed vehicles that plunged 45 metres when the bridge suddenly fell during a downpour on Tuesday.

Officials say 38 people are confirmed killed and 15 injured. They say that 10 to 20 people might be unaccounted-for and the death toll is expected to rise.

Mourners with the coffin of a victim of the bridge collapse
Mourners with the coffin of a victim of the bridge collapse (Antonio Calanni/AP)

The first funerals are being held ahead of a state funeral in Genoa on Saturday to be celebrated by Cardinal Angelo Bagnasco.

The collapse occurred about midday on Tuesday, the eve of Italy’s biggest summer holiday, when traffic was particularly busy on the 51-year-old span that links two highways — one leading to France, the other to Milan — from this north-western port city.

One survivor, whose car plunged from the bridge to the bottom along with falling sections of highway, said that as a trained firefighter he immediately understood that the structure had collapsed when the road dropped out from under him.

“It came down. Everything, the world, came down,” said 33-year-old Davide Capello, who may be the only person to have fallen from the bridge and walked away unharmed.

He was in the middle of the bridge driving towards Genoa when it collapsed.

Italy Bridge Collapse
A digger removes debris of the collapsed Morandi highway bridge in Genoa (Luca Zennaro/ANSA/AP)

“I heard a noise, a dull noise. I saw the columns of the highway in front of me come down. A car in front of me disappeared into the darkness.”

His car plunged nose first, then suddenly stopped with a crash, air bags releasing around him. He said he saw only grey, and outside “there was an unreal silence”.

Mr Capello was released from hospital on Thursday, two days after the collapse, with no major physical injuries.

As the clean-up crews went about their work, authorities were worried about the stability of large remaining sections of the bridge, prompting a wider evacuation order and forcing about 630 people from nearby apartments, some practically in the shadow of the elevated highway.

Firefighters went inside some of the vacated apartments briefly to retrieve documents and, in at least one home, pet cats.

Officials are also urging the quick removal of tons of debris from the dry river bed the bridge had spanned so the rubble does not create a makeshift dam if heavy rain falls in the flood-prone city on the Mediterranean.

Debris also must be cleared from railroad tracks, a vital link especially now Genoa is largely cut in half by the loss of a key artery.

Meanwhile, a mayor in southern Italy has ordered the closure of a bridge designed by the same architect who created the collapsed Genoa bridge.

Italian news agency Ansa quoted Benevento mayor Clemente Mastella saying it is “better to have inconveniences than trouble” for users of his city’s San Nicola bridge while experts check its safety.

The span, designed by Riccardo Morandi, was built in 1955 and reinforced in 2016.