Japanese rescue crews have now confirmed that at least nine people died when a highway tunnel collapsed west of Tokyo on Sunday.
A 50-metre section of the tunnel's concrete ceiling gave way on Sunday morning, crushing at least two vehicles.
Witnesses spoke of terrifying scenes as a van burst into flames, sending out clouds of blinding, acrid smoke.
Authorities say the death toll has now risen to nine.
Five charred bodies were found in the burnt-out van.
Another victim, a truck driver, had called for help using his mobile phone after become trapped in his cab, but was dead by the time search crews reached him.
Two more bodies were found this morning in a car that was crushed by the falling concrete and authorities later confirmed the death of another person.
This morning it was not clear if all the missing people had been accounted for.
"These slabs of concrete that have fallen from the ceiling are quite large and well and truly big enough to cover a car," North Asia correspondent Mark Willacy told ABC News Breakfast.
"I do believe the rescue teams believe they've got most of the bodies out, if not all of them."
Emergency crews who rushed to the five-kilometre Sasago tunnel on Sunday had been hampered by the thick smoke billowing from the entrance.
Dozens of people abandoned their vehicles on the Tokyo-bound section of carriageway and ran for one of the emergency exits or for the mouth, where they huddled in bitter winter weather.
Emergency workers equipped with breathing apparatus battled around a third of the way into the tunnel before engineers warned the structure could be unstable and more debris could fall.
Rescuers were forced to halt their work for several hours as a team of experts assessed the danger.
It was during this inspection that accompanying police officers confirmed the first deaths inside the van.
"What we found resembled bodies inside a vehicle, they were blackened," one official said.
One man who fled the tunnel told Jiji Press he had watched in horror as concrete crashed down onto a vehicle in front of him, leaving little more than a mound of dust and debris.
Voices cried out "Help" and "Anyone please help" from the pile before a young woman emerged with her clothes torn, he was reported as saying.
She could not stop trembling, he told the agency, as he asked her how many had been inside the vehicle.
"She said: 'All of my friends and my boyfriend...Please help them,'" said the man, adding the flames were too strong.
Footage from security cameras in the late afternoon showed large concrete panels in a V shape, apparently having collapsed from the middle, with teams of men in protective gear scrambling over them.
The tunnel is one of the longest in Japan, and connects Tokyo to the country's central and western regions.
Experts speculate that vibrations from earthquakes and passing vehicles may have loosened the concrete ceiling.