At least 19 people were killed when a coach overturned on a remote road in the Argentinian Andes, near the border with Chile, officials say.
A survivor who was not identified said that the coach had been travelling too fast, despite the concerns of passengers.
The crash happened near Aconcagua, the highest mountain outside of Asia.
The Chilean company that operated the vehicle says it is striving to ascertain the identities of the dead.
Mendoza Provincial Governor Alejandro Gulle was quoted by AFP news agency as saying said that two Chilean coach drivers who survived the crash were being questioned in the town of Uspallata, a tourist location near the 6,960m (22,835ft) Mt Aconcagua.
The dead - including three children - are mostly from Argentina but also from Chile, Colombia and Haiti, officials say. The accident happened in good weather on a well maintained road but on a dangerous curve.
"I was sleeping when the bus began to flip over," the unidentified teenaged passenger told Argentina's Channel 13. "[When] I woke up and I was falling.
"[The bus] was going at a high speed. It hit the roadside, first it moved a little bit and then continued. It went very fast, very fast."
The passenger said the bus had continued to travel at speed even though passengers volubly complained.
At least 41 people, most of them police officers, were killed when a bus fell off a bridge in north-west Argentina in December 2015.