KOSHU: Japanese rescuers found several 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-kilometer-long tunnel. Witnesses spoke of terrifying scenes as one vehicle burst into flames, sending out clouds of blinding, acrid smoke.

Rescuers were forced to suspend for several hours their efforts to reach those believed trapped under thick concrete ceiling panels that crashed from the roof of the tunnel, as engineers warned more debris could fall.

Emergency crews who rushed to the Sasago tunnel on the Chuo Expressway, 80 kilometers 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 up to 70 meters 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 suspend their work as a team of experts assessed the danger.

Cameras inside the tunnel earlier showed an ambulance and several firefighters wearing protective gear, working in     a section where cars sat with their lights flashing, shrouded in smoke.

At least three people were taken to hospital, including one 28-year-old woman who emerged from the smoke-darkened tunnel by herself.

The woman told the fire rescue unit that she had been traveling in a rented van with five other people, fire department official Kazuya Tezuka said.

“I have no idea about what happened to the five others. I don’t know how many vehicles were ahead and behind ours,” she was quoted as saying.

A truck driver who managed to telephone a colleague from inside the tunnel was also believed to be trapped and emergency services said that they were on their way to get him.

Two large orange emergency structures had been erected at the tunnel mouth and a helicopter remained nearby, apparently ready to ferry the injured to hospital.

The tunnel, which passes through hills not far from Mt. Fuji, is one of the longest in Japan. It sits on a major road connecting Tokyo with the center and west of the country.

Japan has an extensive and well-maintained network of highways throughout its mountainous terrain, with thousands of tunnels, usually several hundred meters long. Millions of cars use the network every day.