In this handout image provided by the Police of Swiss canton Valais the wreckage of a bus is seen after it crashed inside a motorway tunnel on March 13, 2012 in Sierre, Switzerland. 28 people, including 22 children, returning from a skiing holiday died in this bus accident. (Photo by Police Cantonale Valaisanne via Getty Images)

Messages and tributes drawn by school children adorn the gates of Sint Lambertus School, following a bus crash that killed 22 children in Switzerland, on March 14, 2012 in Heverlee, Belgium. The accident occurred when a school bus carrying 11 –12 year olds, returning from a skiing holiday, crashed into a tunnel wall, killing 28 of the 52 passengers. (Photo by Herman Ricour /Getty Images)