Police officers and firefighters gather in front of the Sasago Tunnel on the Chuo Expressway in Otsuki, Yamanashi prefecture, in this photo taken by Kyodo December 2, 2012. (Photo: Reuters)
Japanese rescuers found five charred bodies in a highway tunnel that collapsed on Sunday, crushing cars and triggering a blaze, and sparking fears of another cave-in.
At least seven people were missing inside the nearly five-kilometre (three mile)-long tunnel. Witnesses spoke of terrifying scenes as at least one vehicle burst into flames, sending out clouds of blinding, acrid smoke.
For several hours rescuers were forced to suspend their efforts to reach those believed trapped under the more-than one tonne concrete ceiling panels that crashed from the roof as engineers warned more debris could fall.
Emergency crews who rushed to the Sasago tunnel on the Chuo Expressway, 80 kilometres (50 miles) west of the capital, were hampered by 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 crews equipped with breathing apparatus battled around a third of the way into the tunnel, where they found 110 metres (yards) of concrete panels had come crashing down, crushing at least two vehicles.
Hours after the collapse, engineers warned the structure could be unstable, forcing rescuers to halt their work as a team of experts assessed the danger.
It was during this inspection that accompanying police officers confirmed the first deaths.
"What we found resembled bodies inside a vehicle, they were blackened. We have visually confirmed them but have yet to take them out for closer examination," an official told AFP.
The Fire and Disaster Management Agency later confirmed there were five bodies, adding another vehicle had also been burned.
One man who fled the tunnel told the Jiji Press news agency 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.
A fire department official said workers were still trying to reach a van in which at least one person was believed trapped.
Chikaosa Tanimoto, professor emeritus of tunnel engineering at Osaka University told NHK the concrete panels are suspended from pillars.
"It is conceivable that the parts connecting the ceiling panels and pillars, or pillars themselves, have deteriorated, affected by vibrations from earthquakes and passing vehicles," he said.
An official from highways operator NEXCO said material degradation was a possibility, adding the risk of further collapse remained. His colleague said the ceiling had undergone its regular five-yearly inspection in September this year.
An AFP reporter said two large orange tents had been erected at the tunnel mouth and a helicopter remained nearby, ready to ferry the injured to hospital.
The tunnel, which passes through hills near Mount Fuji, is one of the longest in Japan. It sits on a major road connecting Tokyo with the centre and west of the country.
A man in his 30s, who was just 50 metres (yards) ahead of the caved-in spot, recounted details of the terrifying experience.
"A concrete part of the ceiling fell off all of a sudden when I was driving inside. I saw fire coming from a crushed car. I was so frightened I got out of my car right away and walked one hour to get outside," he told NHK.
Japan has an extensive web of highways with thousands of tunnels, usually several hundred metres long. Millions of cars use the network every day.