Many of the people killed or injured in Friday's horrific bus crash in Nagano Prefecture may not have been wearing seat belts, as required by law.

The Road Traffic Law, which was revised in 2008, requires bus drivers to ask passengers to wear seat belts on all buses, with the exception of those that run only on local streets. Many drivers, however, are lax in enforcing this rule.

A number of passengers aboard the Nagano-bound bus said neither of the two drivers made such a request during the trip. Fourteen people, including the two drivers, were killed.