TOKYO Tokyo police are searching the offices of the operator of a tunnel where hundreds of concrete ceiling slabs collapsed onto moving vehicles below, killing nine people.
Those killed in Sunday's accident were traveling in three vehicles in the 3-mile long Sasago Tunnel about 50 miles west of Tokyo. The tunnel, on a highway that links the capital to central Japan, opened in 1977.
About a dozen uniformed police were shown on television entering the headquarters of Central Japan Expressway Co. early Tuesday, toting cardboard and plastic boxes.
"Yes they are searching our offices here. We will be fully cooperating with them," said Osamu Funahashi, an official at the government-owned company.
Japanese officials are also inspecting many of the other tunnels. There are 49 other tunnels around the country that are either on highways or roads managed by the central government
In addition to the nine deceased, two other victims were sent to the hospital for injuries.
Two vehicles also caught fire, and initial recovery efforts were slowed due to heavy smoke. Efforts have since been suspended while the ceiling is shored up to prevent more pieces from falling in the road.
Japanese officials say the location of the accident about half-way through the tunnel has also made work difficult. The tunnel in the other direction is also closed.
According to the Wall Street Journal, about 270 one ton concrete slabs fell over a 360-foot part of the tunnel.
People who were in the tunnel at the time of the incident and were able to get out said that drivers were going the wrong way on the road trying to escape, the Guardian reported. Many people cried for help underneath the rubble. One man said that he was so frightened he abandoned his car and walked one hour to get out of the tunnel.
Ryoichi Yoshizawa , a spokesman for Central Japan Expressway Company or NEXCO-Central, told CNN that "anchor bolts" used to hold the concrete slabs to the tunnel ceiling may be to blame. He added the weathered of the bolts or concrete slabs could have contributed to the accident. While visual checks were regularly performed, there had not been a physical check of the bolts for quite some time.
"There were parts of concrete (slabs) where bolts had fallen off," Yoshizawa said.
Another possible explanation is that the recent 4.9 Tokyo earthquake on Nov. 24 may have loosened the foundation and structure of the tunnel, the Guardian reports.
Authorities say it's not clear if there are other survivors but work is slated to resume later in the day.