At least five people are feared trapped inside a collapsed motorway tunnel about 80 kilometres west of the Japanese capital.
The incident took place at around 08:00 am Sunday (local time).
Multiple news services say that a “100m (328ft) section of the tunnel caved in on the Tokyo-bound lanes on the Chuo Expressway, in Yamanashi prefecture.”
The BBC reports that Japanese public broadcaster NHK said black smoke was coming out of the tunnel and that a fire was ongoing inside.
One on-site traffic police official told the AFP news agency, “we don’t know exactly how many vehicles are on fire.”
That same official said a woman was taken to hospital after making her way out of the tunnel by herself. Briefly interviewed on the spot, the woman said she had been travelling with five other people in a van, adding:
“I have no idea about what happened to the five others. I don’t know how many vehicles were ahead and behind ours.”
Another survivor told NHK that he witnessed “a concrete part of the ceiling fall off all of a sudden when I was driving inside. I saw a fire coming from a crushed car”.
That same survivor said he walked for an hour to get out of the tunnel.
The Sasago tunnel is an estimated 4.3km-long (2.7 miles) and is one the major dual highways out of Tokyo. Firefighters are currently working on the closed highway to put out the blaze.