Speaking to the faithful in St. Peter's Square, Francis expressed his "spiritual closeness" to the victims, the injured and their families, and the hundreds of local people who were forced to evacuate their homes in the area. The collapse appears not to have killed anyone under the road, but only those who were driving on it, the civil protection agency said earlier.
"The latest official number is 35 but we can't rule out that it could rise further", a spokesman for the police in Genoa said.
It was unclear what had caused the collapse, but the event raised questions among some Italian government officials about maintenance of their country's infrastructure - a common concern in developed countries, where numerous major roadways were built decades ago.
"We should ask ourselves whether respecting these limits is more important than the safety of Italian citizens".
Similar calls on the management of Autostrade to step down and threats of possible withdrawal of its license to operate the country's highways came from the deputy premier Luigi Di Maio and Matteo Salvini, heads respectively of the ruling coalition's partners Five Star Movement and League.
"If they are not able manage our highways, the state will do it", Toninelli said.
Between 30 and 35 cars and three heavy vehicles were on the bridge at the time of the collapse. "It seemed like a scene from a film, it was the apocalypse", Mr Capello, who is from Sardinia, said.
Cars and trucks were tangled in the rubble and nearby buildings damaged by vast chunks of concrete, according to an AFP photographer at the scene.
"Firefighters are working together and teams of rescuers and police sniffer dogs have been mobilised", emergency services said on Twitter.
The Italy built in the 1950s and 1960s is in urgent need of renovation.
The highway bridge was erected in the 1960s, the company, Autostrade per l'Italia, said.
At the Vatican, Pope Francis led prayers Wednesday for the victims of the Genoa bridge collapse. "The bridge was constantly monitored and supervised well beyond what the law required".
Many in the city had said the 1967 bridge needed shoring up.
Autostrade said the bridge maintenance programme had been based on the results of its regular checks and had also been approved by the transport ministry.
The design of the bridge has been criticized in the past.
In another video, rescuers worked to free other victims trapped between rubble, under very big concrete slabs criss-crossed with steel wires to reinforce them.
"There will be a time when maintenance costs will exceed those of reconstruction, and then we will have to proceed with the replacement".
Restructuring work on the bridge was carried out in 2016.
Mehdi Kashani, an associate professor in structural mechanics at the University of Southampton in the United Kingdom, said pressure from "dynamic loads", such as heavy traffic or strong winds, could have resulted in "fatigue damage" in the bridge's parts.
The government has pledged to increase public investments and lobby the European Commission to have the extra spending excluded from EU deficit calculations.
The Morandi bridge carries a major road, the A10 toll motorway, which serves the Italian Riviera and links northern Italy to France.