Swiss rail authorities spent Saturday trying to determine what caused the Glacier Express train to derail, killing one person and injuring 42 others.
The train crashed Friday near Fiesch while traveling between Zermatt and St. Moritz, near the Italian border, SkyNews reported.
Police said a dozen passengers were in serious condition.
Officials reported two cars derailed and a third overturned. However,SkyNews reported photos showed at least two cars had tipped over.
The train, which travels at an average speed of just 18 miles per hour, was carrying mostly Japanese tourists. Kyodo News reported the fatality was a 64-year-old Japanese woman.