At least nine bodies have been found after parts of a tunnel collapsed on a highway west of Tokyo, trapping vehicles, according to the national broadcaster NHK.

Japanese emergency officials discovered five bodies in a van, a body of a man in a cooler truck and three other bodies in a car, according to the website NHK English. Officials say 30 cars are involved.

The tunnel collapsed early Sunday morning, trapping vehicles as smoke from a fire inside initially prevented rescuers from approaching.

Video footage from cameras inside the tunnel, after the fire was extinguished, showed firefighters picking their way through concrete roof panels that collapsed onto vehicles inside the Sasago Tunnel, about 80 kilometres outside the city.

The Fire and Disaster Management Agency issued a statement Sunday saying five people were confirmed to have been in a car that burned inside the tunnel, and at least one other was in a truck.

The agency also said two people were confirmed injured, one of them moderately.

A woman who escaped from her rental car after it was trapped in the 4.3-kilometre-long tunnel told authorities she was unsure about the condition of five other people who had been in the vehicle with her.

Executives for Central Japan Expressway Co. said the company was investigating why the concrete panels had given way. A check of the tunnel's roof in September and October found nothing amiss, they told the Associated Press.

Approximately 150 panels fell from the roof, affecting about 110 metres of the tunnel.

Police vehicles, fire trucks and ambulances were massed outside the tunnel's entrance. A man who said he saw the collapse and alerted authorities to the emergency told NHK television he managed to escape after he was ordered to flee.

The roof and windows of another vehicle parked on the roadside outside the tunnel were crushed, and the injured occupants reportedly taken to a hospital.

The Sasago Tunnel, which opened in 1977, is one of many along Japan's mountainous landscape. It is widely used, with tens of thousands of cars likely passing through in a single weekend, according to local media.

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  • This image taken from the monitoring camera of Central Nippon Expressway's Hachioji branch, Tokyo, shows the fallen roof panels in the Sasago Tunnel, Yamanashi Prefecture, central Japan, Sunday, Dec. 2, 2012. At least seven people were feared missing after parts of a tunnel collapsed Sunday on the highway west of Tokyo, trapping vehicles as smoke from a fire inside initially prevented rescuers from approaching. The words at bottom read: Sasago Tunnel (To Tokyo). (AP Photo/Kyodo News) JAPAN OUT, MANDATORY CREDIT, NO LICENSING IN CHINA, FRANCE, HONG KONG, JAPAN AND SOUTH KOREA

  • Police officers and firefighters gather at the exit of the Sasago Tunnel on the Chuo Expressway in Otsuki, Yamanashi Prefecture, central Japan, Sunday morning, Dec. 2, 2012. Police said that parts of the tunnel collapsed Sunday morning, trapping an unknown number of vehicles as smoke from a fire inside prevented rescuers from approaching. (AP Photo/Kyodo News) JAPAN OUT, MANDATORY CREDIT, NO LICENSING IN CHINA, FRANCE, HONG KONG, JAPAN AND SOUTH KOREA

  • Smoke billows out of the Sasago Tunnel on the Chuo Expressway in Koshu, Yamanashi Prefecture, central Japan, Sunday morning, Dec. 2, 2012. A part of the tunnel collapsed Sunday morning, possibly involving several vehicles and injuring several people, local media said. (AP Photo/Kyodo News) JAPAN OUT, MANDATORY CREDIT, NO LICENSING IN CHINA, FRANCE, HONG KONG, JAPAN AND SOUTH KOREA

  • Aerial

    Firefighters and rescuers, top, prepare for rescue operation near the Sasago Tunnel on the Chuo Expressway in Koshu, Yamanashi Prefecture, central Japan, Sunday, Dec. 2, 2012. A part of the tunnel collapsed Sunday morning, possibly involving several vehicles and injuring several people, local media said. (AP Photo/Kyodo News) JAPAN OUT, MANDATORY CREDIT, NO LICENSING IN CHINA, FRANCE, HONG KONG, JAPAN AND SOUTH KOREA

  • Firefighters and police gather at the entrance of the Sasago Tunnel on the Chuo Expressway in Koshu, Yamanashi Prefecture, central Japan, Sunday, Dec. 2, 2012. A part of the tunnel collapsed Sunday morning, possibly involving several vehicles and injuring several people, local media said. (AP Photo/Kyodo News) JAPAN OUT, MANDATORY CREDIT, NO LICENSING IN CHINA, FRANCE, HONG KONG, JAPAN AND SOUTH KOREA

  • Police vehicles are parked at the entrance as smoke billows out of the Sasago Tunnel on the Chuo Expressway in Koshu, Yamanashi Prefecture, central Japan, Sunday, Dec. 2, 2012. A part of the tunnel collapsed Sunday morning, possibly involving several vehicles and injuring several people, local media said. (AP Photo/Kyodo News) JAPAN OUT, MANDATORY CREDIT, NO LICENSING IN CHINA, FRANCE, HONG KONG, JAPAN AND SOUTH KOREA

  • JAPAN-ROAD-ACCIDENT-TUNNEL-FIRE

    Rescue workers and police gather outside the Sasago tunnel along the Chuo highway near the city of Otsuki in Yamanashi prefecture, 80 kms west of Tokyo on December 2, 2012 after part of the tunnel collapsed. Japanese rescuers found several charred bodies in the highway tunnel that collapsed early in the day, crushing cars and triggering a blaze, and sparking fears of another cave-in. AFP PHOTO / Yoshikazu TSUNO (Photo credit should read YOSHIKAZU TSUNO/AFP/Getty Images)

  • JAPAN-ROAD-ACCIDENT-TUNNEL-FIRE

    Police and fire workers stand alongside emergency services vehicles outside the entrance of the collapsed Sasago tunnel (back) on the Chuo expressway in Koshu city, Yamanashi prefecture, west of Tokyo on December 2, 2012. Seven people are missing after concrete ceiling panels along a section of highway tunnel collapsed in Japan. The accident occurred on Tokyo-bound lanes inside the Sasago tunnel on the Chuo Expressway, some 80 kilometres (50 miles) west of the capital, at around 8:00 am on December 2, an official at the expressway traffic police said. AFP PHOTO / JIJI PRESS ==JAPAN OUT== (Photo credit should read JIJI PRESS/AFP/Getty Images)

  • JAPAN-ROAD-ACCIDENT-TUNNEL-FIRE

    Rescue workers and police gather outside the Sasago tunnel along the Chuo highway near the city of Otsuki in Yamanashi prefecture, 80 kms west of Tokyo on December 2, 2012 after part of the tunnel collapsed. Japanese rescuers found several charred bodies in the highway tunnel that collapsed early in the day, crushing cars and triggering a blaze, and sparking fears of another cave-in. AFP PHOTO / Yoshikazu TSUNO (Photo credit should read YOSHIKAZU TSUNO/AFP/Getty Images)

  • JAPAN-ROAD-ACCIDENT-TUNNEL-FIRE

    Rescue workers and police gather outside the Sasago tunnel along the Chuo highway near the city of Otsuki in Yamanashi prefecture, 80 kms west of Tokyo on December 2, 2012 after part of the tunnel collapsed. Japanese rescuers found several charred bodies in the highway tunnel that collapsed early in the day, crushing cars and triggering a blaze, and sparking fears of another cave-in. AFP PHOTO / Yoshikazu TSUNO (Photo credit should read YOSHIKAZU TSUNO/AFP/Getty Images)

  • JAPAN-ROAD-ACCIDENT-TUNNEL-FIRE

    Police vehicles block the road leading to the entrance of the collapsed Sasago tunnel on the Chuo expressway in Koshu city, Yamanashi prefecture, some 80-kilometres west of Tokyo on December 2, 2012 after a 100-metre long section of highway tunnel collapsed. At least seven people are missing after concrete ceiling panels along a section of highway tunnel collapsed in Japan on December 2. AFP PHOTO / Yoshikazu TSUNO (Photo credit should read YOSHIKAZU TSUNO/AFP/Getty Images)

  • JAPAN-ROAD-ACCIDENT-TUNNEL-FIRE-MISSING

    Fire workers prepare for their rescue operation outside the exit of the collapsed Sasago tunnel on the Chuo expressway in Otsuki city, Yamanashi prefecture, some 80-kilometre west of Tokyo on December 2, 2012. At least seven people are missing after concrete ceiling panels along a section of highway tunnel collapsed in Japan. The accident occurred on Tokyo-bound lanes inside the Sasago tunnel on the Chuo Expressway, some 80 kilometres (50 miles) west of the capital, at around 8:00 am on December 2, an official at the expressway traffic police said. ==JAPAN OUT== AFP PHOTO / YOMIURI SHIMBUN (Photo credit should read YOMIURI SHIMBUN/AFP/Getty Images)

  • JAPAN-ROAD-ACCIDENT-TUNNEL-FIRE

    Rescue workers and policeman gather alongside emergency services vehicles on the road leading to the entrance of the collapsed Sasago tunnel on the Chuo expressway in Koshu city, Yamanashi prefecture, some 80-kilometres west of Tokyo on December 2, 2012. At least seven people are missing after concrete ceiling panels along a section of highway tunnel collapsed in Japan on December 2. AFP PHOTO / Yoshikazu TSUNO (Photo credit should read YOSHIKAZU TSUNO/AFP/Getty Images)

  • JAPAN-ROAD-ACCIDENT-TUNNEL-FIRE-MISSING

    Smoke billows from the entrance of the collapsed Sasago tunnel as police and fire workers (bottom) gather in preparation for their rescue operation on the Chuo expressway in Koshu city, Yamanashi prefecture, some 80-kilometre west of Tokyo on December 2, 2012. At least seven people are missing after concrete ceiling panels along a section of highway tunnel collapsed in Japan. The accident occurred on Tokyo-bound lanes inside the Sasago tunnel on the Chuo Expressway, some 80 kilometres (50 miles) west of the capital, at around 8:00 am on December 2, an official at the expressway traffic police said. ==JAPAN OUT== AFP PHOTO / Motoki Nakashima / YOMIURI SHIMBUN (Photo credit should read Motoki Nakashima/AFP/Getty Images)

  • JAPAN-ROAD-ACCIDENT-TUNNEL-FIRE

    Police officers (L) walk on the road leading to the entrance (R) of the collapsed Sasago tunnel on the Chuo expressway in Koshu city, Yamanashi prefecture, some 80-kilometres west of Tokyo on December 2, 2012. At least seven people are missing after concrete ceiling panels along a section of highway tunnel collapsed in Japan on December 2. AFP PHOTO / Yoshikazu TSUNO (Photo credit should read YOSHIKAZU TSUNO/AFP/Getty Images)

  • JAPAN-ROAD-ACCIDENT-TUNNEL-FIRE

    Rescue workers and policeman gather alongside emergency services vehicles on the road leading to the entrance of the collapsed Sasago tunnel on the Chuo expressway in Koshu city, Yamanashi prefecture, some 80-kilometres west of Tokyo on December 2, 2012. At least seven people are missing after concrete ceiling panels along a section of highway tunnel collapsed in Japan on December 2. AFP PHOTO / Yoshikazu TSUNO (Photo credit should read YOSHIKAZU TSUNO/AFP/Getty Images)

  • JAPAN-ROAD-ACCIDENT-TUNNEL-FIRE

    Rescue workers and policeman gather alongside emergency services vehicles on the road leading to the entrance of the collapsed Sasago tunnel on the Chuo expressway in Koshu city, Yamanashi prefecture, some 80-kilometres west of Tokyo on December 2, 2012. At least seven people are missing after concrete ceiling panels along a section of highway tunnel collapsed in Japan on December 2. AFP PHOTO / Yoshikazu TSUNO (Photo credit should read YOSHIKAZU TSUNO/AFP/Getty Images)

  • Police officers and firefighters gather at the exit of the Sasago Tunnel on the Chuo Expressway in Otsuki, Yamanashi Prefecture, central Japan, Sunday morning, Dec. 2, 2012. Police said that parts of the tunnel collapsed Sunday morning, trapping an unknown number of vehicles as smoke from a fire inside prevented rescuers from approaching. (AP Photo/Kyodo News) JAPAN OUT, MANDATORY CREDIT, NO LICENSING IN CHINA, FRANCE, HONG KONG, JAPAN AND SOUTH KOREA

  • JAPAN-ROAD-ACCIDENT-TUNNEL-FIRE

    A policeman stands guard in front of emergency service vehicles on the road leading to the entrance of the collapsed Sasago tunnel on the Chuo expressway in Koshu city, Yamanashi prefecture, some 80-kilometres west of Tokyo on December 2, 2012. At least seven people are missing after concrete ceiling panels along a section of highway tunnel collapsed in Japan on December 2. AFP PHOTO / Yoshikazu TSUNO (Photo credit should read YOSHIKAZU TSUNO/AFP/Getty Images)

  • Police vehicles are parked at the entrance as smoke billows out of the Sasago Tunnel on the Chuo Expressway in Koshu, Yamanashi Prefecture, central Japan, Sunday morning, Dec. 2, 2012. A part of the tunnel collapsed Sunday morning, possibly involving several vehicles and injuring several people, local media said. (AP Photo/Kyodo News) JAPAN OUT, MANDATORY CREDIT, NO LICENSING IN CHINA, FRANCE, HONG KONG, JAPAN AND SOUTH KOREA