TOKYO—Parts of a tunnel collapsed Sunday on a highway west of Tokyo, trapping an unknown number of vehicles as smoke from a fire inside initially prevented rescuers from approaching.

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

About 25 vehicles were inside the 4.3-kilometre tunnel, some of them trucks stopped by the tunnel’s collapse.

A police spokesman said they were still seeking details about the situation inside 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.

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