A lawsuit has been filed in the U.S. against the Vancouver-based tour bus company involved in a crash that killed nine people in Oregon on Dec. 30.

The lawyer for two Korean exchange students who survived the crash alleges the Canadian driver was exhausted and was speeding during hazardous conditions before the bus smashed through a barrier and rolled down a hill near Pendleton, Oregon.

The students, Jong-Hyun Chae and Seong-June An, were injured in the crash, which occurred during a trip from Las Vegas to B.C.

The tour bus was owned by Mi Joo Tour & Travel in Vancouver, where the 54-year-old driver also lives.