The official said that the accident occurred at 00:41 a.m. local time (0541 GMT) on Monday, when the bus, which was heading from Lima toward the city of Arequipa, crashed into several other vehicles.
According to Munoz Lozada, two people severely injured in the accident were taken to Nazca Hospital near Arequipa, where they received emergency care.
There were four foreign tourists among the injured, including two Brazilians.
The manager of the Superintendency of Ground Transportation of People, Cargo and Merchandise, Jorge Beltran, said that a possible cause of the accident was the driver's excessive speed, as the vehicle was travelling at over 100 km per hour.
Peru's highways have seen frequent fatal accidents as many of the nation's roadways pass through the dangerous Andes Mountains.