At least seven people were missing inside the nearly 5km-long tunnel. Witnesses spoke of terrifying scenes as at least one vehicle burst into flames, sending out clouds of blinding, acrid smoke.
Rescuers were forced to suspend work for several hours their efforts to reach those believed trapped under thick concrete ceiling panels that crashed from the roof of the tunnel when engineers warned more debris could fall.
Emergency crews who rushed to the Sasago tunnel on the Chuo Expressway, 80km west of the capital, were hampered by thick smoke billowing from the entrance.
