Updated at 10:50 p.m. ET: TOKYO — A tunnel on a major highway in central Japan collapsed on Sunday, killing nine people and starting a blaze, Japanese media reported.

Rescue efforts  inside the smashed tunnel, which began spewing smoke after concrete ceiling panels fell onto the road, were delayed by the fallen debris, public broadcaster NHK reported. 

Nine bodies were recovered, including five from a burned van and three more from another vehicle, according to news reports. 

The fire service earlier said at least seven people were unaccounted for in the 2.8-mile tunnel in Yamanashi prefecture, about 50 miles west of Tokyo on the Chou Expressway, a main road connecting the capital to western Japan.

The fire service said the blaze was extinguished about 11 a.m. (9 p.m. ET) —some three hours after the accident occurred.  

"Dense smoke was coming out as if it covers the entire mountain," witness Kiyoko Toyomura told Japanese news agency Kyodo. 

Motorists described narrow escapes from falling debris, and a long walk through the darkness after abandoning their cars.

Jiji Press / AFP - Getty Images

A screen grab taken from video from highway operator Central Nippon Expressway Company shows a passenger vehicle stopping in front of the collapsed roof inside the highway tunnel.

"When I was driving in the tunnel, concrete pieces fell down suddenly from the ceiling," a man in his 30s told NHK. "I saw a crushed car catching fire. I was frightened, left my car and walked for about an hour to get out of the tunnel." 

NHK reporter Yoshio Goto, caught in Sunday's accident, hit the accelerator and managed to drive out.

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"But it was a bit too late and pieces of ceiling fell on my car. I kept pressing the pedal and managed to get out," he said. "Then when I looked around, I saw half of the car ceiling was crushed."

It was the worst such accident in Japan since 1996, when a tunnel collapsed and falling rocks crushed cars and a bus, killing 20 people. 

NBC News's Arata Yamamoto contributed to this report from Reuters.

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