One person was killed and 21 others were injured in a collision involving a truck of Japan's Ground Self-Defense Force and a tourist bus Saturday morning in Kumamato Prefecture in southwestern Japan, local press reported.

The accident occurred at around 8:35 a.m. local time when the truck and the bus carrying some 40 passengers collided inside a tunnel on the Kyushu Expressway near the city of Yatsushiro, the report said, adding that a 39-year-old tour conductor on the bus was killed and 21 passengers were injured, one of them seriously..

The accident happened when the GSDF truck changed lanes and hit the bus which was in the overtaking lane. One of the two men on the truck told local police after the accident that the truck driver changed lanes to avoid something like a towel falling from above.