Kyodo News reported police confirmed there were nine bodies in three vehicles trapped in the 2 1/2-mile-long Sasago Tunnel on the Chuo Expressway in Yamanashi prefecture.
The Japanese broadcaster NHK reported emergency officials found five bodies in a van, the body of a man in a refrigerated truck and three other bodies in a car.
NHK said there were about 30 vehicles in the tunnel when 150-200 feet of the concrete ceiling collapsed about 8 a.m. Sunday.
Kyodo said the five victims in the one vehicle included three men and two women, all in their 20s from Tokyo. The Japanese news service said one 28-year-old woman in that vehicle got out alive.
The Japanese news service said two women were taken to a hospital with injuries. One had moderate injuries and the other had minor injuries.
Highway security cameras showed large columns of black smoke pouring out of the tunnel, which was opened to traffic in 1977, that prevented firefighters from entering to search for victims.
NHK said there were reports of other people making their way out of the tunnel following collapse and subsequent fire. The Japanese broadcaster said the smoke kept rescuers hundreds of feet away and traffic on the highway was closed in the vicinity.