A tire blew out on the eastbound truck, which then jumped the grass median and struck the Greyhound bus traveling in the opposite direction, New Mexico State Police Officer Ray Wilson told a news conference.
The bus was carrying 49 passengers, a Greyhound spokeswoman said. It collided with the truck around 12:30 p.m. on Interstate 40 near the city of Thoreau, located about 100 miles west of Albuquerque, the state police said.
All but six people on the bus were taken to area hospitals, said Wilson, who said the death toll was expected to rise.
Greyhound Lines spokeswoman Crystal Booker said the bus was headed from Albuquerque to Phoenix. She deferred comment regarding the crash to the state police.