At least 35 people were killed when a bridge collapsed in Italy, police said, after firemen worked through the night looking for any survivors buried under the rubble.
"The latest official number is 35 but we can't rule out it could rise further," a spokeswoman for the police in Genoa said.
Reports said cries could be heard from people trapped in the debris. The number missing ranges from four to 12.
Genoa police spokesperson Alessandra Bucci told Reuters it was thought that people were still alive.
About 250 firefighters from across Italy are taking part in the search, using sniffer dogs and climbing gear.
"We're not giving up hope," fire official Emanuele Giffi told AFP news agency, vowing teams would work "round the clock until the last victim is secured".
More than 400 people have been evacuated amid fears other parts of the bridge might fall.
The cause of the disaster, which occurred during torrential rain, was not immediately clear but questions had been raised about the safety of the structure.
The Morandi Bridge, built in the 1960s, stands on the A10 toll motorway, an important conduit for goods traffic from local ports, which also serves the Italian Riviera and southern coast of France.
Interior Minister Matteo Salvini has vowed to bring anyone responsible for the collapse to book.
Mr Salvini said three children, aged eight, 12 and 13 were among the dead.
The Italian fire service tweeted a video of one person being extracted and carefully lowered on cables from a shattered vehicle, which was suspended in the wreckage of the bridge, high above the ground.
#15ago #Genova crollo viadotto #Morandi: senza sosta nella notte il lavoro dei 240 #vigilidefuoco, squadre #usar e #cinofili alla ricerca di dispersi sotto le macerie. L’intervento prosegue, immagini complete su https://t.co/39yWOHsswT pic.twitter.com/5x8w9ubhmy— Vigili del Fuoco (@emergenzavvf) August 15, 2018
Between 30 and 35 cars and three heavy vehicles were on the bridge at the time of the collapse.
A huge tower and sections of the bridge collapsed on to railway lines, a river and a warehouse.
The car of Davide Capello, 33, a former goalkeeper for Serie A side Cagliari, came down in the collapse but he survived.
"I was able to get out... I don't know how my car wasn't crushed. It seemed like a scene from a film, it was the apocalypse," he said.
Marcello de Angelis, who is co-ordinating the Italian Red Cross rescue effort, told the BBC that rescuers were treating the disaster like an earthquake.
"There might be the possibility of some niches being created by the rubble itself, with people being protected by the rubble," he said.
"The units that we have sent we use during earthquakes. So it is the same sort of situation - and also the risk of other collapses, obviously, is the same."
How did the structure collapse?
It fell around 11:30am local time during heavy rain. Police reported a violent cloudburst.
"We saw lightning strike the bridge," eyewitness Pietro M all'Asa was quoted as saying by Ansa. "And we saw the bridge going down."
Another witness, unnamed, recalled: "We heard an incredible roar and first we thought it was thunder very close by.
"We live about 5km [three miles] from the bridge but we heard a crazy bang... We were very scared... Traffic went completely haywire and the city was paralysed."
One image posted by the regional emergency services shows a truck perched at the end of the surviving bridge section immediately before the drop.
What do we know of the victims?
A child is among the dead, said the head of the civil defence agency, Angelo Borrelli.
Between 30 and 35 cars and three heavy vehicles were on the bridge at the time of the collapse, he said.
The full horror of the collapse could be seen in aerial video of the scene.
Patrick Villardry, a French firefighter who came from Nice to help the rescue effort, told AFP news agency the task was huge.
"The first victims have been evacuated and now we have to search under the wreckage of buildings, but there are thousands of tonnes of concrete," he said.
Aerial footage taken by the fire service and shown on Italian news services showed the scale of the destruction.
How important is the bridge?
The Morandi Bridge, built in the 1960s, stands on the A10 toll motorway, which serves the Italian Riviera and southern coast of France.
The missing section was dozens of metres in length, and ran across the span of the Polcevera river.
Its collapse of the bridge was an "incident of vast proportions on a vital arterial road, not just for Genoa, but for the whole country", said the governor of the Liguria region, Giovanni Toti.
"The Morandi bridge connects three major ports in our country, used by tens, even hundreds of thousands of people. They depart from these ports on holiday. These docks receive most of our country's imported goods. It damages the very structure of the Italian logistics system. We are expecting a very fast response from the government."
Mr Borrelli said the authorities were trying to arrange help for those affected by the disaster, as well as setting up diversions for traffic.
"What we are carrying out at the moment is a search and rescue operation for the victims and the injured, to get the victims out and recover the injured," he said.
"Then we are obviously also trying to work out how to set up a viable route that is an alternative to the motorway, and also for entry and exit from the port."
How has the world reacted?
French President Emmanuel Macron tweeted a message of sympathy to the people of Italy, writing in both Italian and French. He said France was ready to offer any necessary aid.
European Commission chief Jean-Claude Juncker voiced his "deepest sympathy and sincere condolences to the families and friends of those who have died, and to the Italian people".
Were there any concerns about the bridge?
Restructuring work on the bridge was carried out in 2016, Reuters news agency reports.
The highway operator said work to shore up its foundation was being carried out at the time of the collapse, and the bridge was constantly monitored.
"It's not acceptable that such an important bridge... was not built to avoid this kind of collapse," Mr Rixi was quoted as saying by Reuters.
Italy's recently installed government has pledged to increase public investment in infrastructure.
The country spent more than €14bn (£12.5bn; $16bn) on its roads in 2006 but that had dropped to less than €4bn by 2010, according to data from the Organisation for Economic Co-operation and Development.
The figures cover spending on new transport construction and the improvement of the existing networks.
Spending started to increase in 2013, when total spend was less than Spain, Germany, France and the UK.
- BBC / Reuters