Story highlights 5 of the bodies are found in a burned station wagon, police say

An inspection of the tunnel occurred a few months ago, a company official says

The partial cave-in was on the Chuo Expressway 50 miles west of Tokyo

It's not clear what caused the collapse, or when the tunnel might reopen

Nine bodies -- eight of them burned -- have been pulled from vehicles crushed in a tunnel collapse about 80 kilometers (50 miles) west of Tokyo, a highway police spokesperson said early Monday.

Five of those were recovered in one charred station wagon, and three others were in another burned vehicle, according to the police spokesperson. The other fatality was in a truck.

The Sasago tunnel on the Chuo Expressway remained closed Monday morning, one day after the cave-in occurred on the highway's Tokyo-bound lanes, Otsuki police said.

Officials from the East Yamanashi Fire Department said the section of concrete that fell was about 50 to 60 meters long and about 20 centimeters (8 inches) thick.

Soon after the collapse, Japanese public broadcaster NHK aired images showing smoke rising, a blue car with its side smashed in, and emergency vehicles on the scene.

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Crews worked through the night trying to get to victims, all the while wary that the tunnel might collapse further. Those efforts continue, and authorities have not said if they believe more bodies will be found.

The privately held Central Nippon Expressway Company operates the 4.7-kilometer-long Sasago tunnel, among others, as well as expressways and toll roads around Japan.

Central Nippon Expressway conducts annual inspections of the tunnel, with one particularly thorough inspection held every five years, a company spokesperson said. A more intensive inspection of the Sasago tunnel was held sometime in the past two to three months, the spokesperson added.

The Chuo Expressway is a particularly busy stretch of highway that runs between Tokyo and, among other places, Mount Fuji.

While it is a ways from the Japanese capital, the partial tunnel collapse and its subsequent closure is expected to cause major traffic and other headaches, especially for those who rely on it for business.

Authorities have not given any indication as to when they expect the tunnel to reopen, nor is it clear why the collapse occurred.