Sixteen people were also injured in the pre-dawn accident on the road between Ibri and Fahud, police said in a statement.
The bus was carrying passengers from Salalah in southwestern Oman to Dubai, the Times of Oman reported, citing the Gulf Transport Company which operates the service.
The dead included six Omanis, four Saudis, two Pakistanis and a Yemeni, police said, adding that the injured included 11 Omanis, two Saudis, a Chinese and a Pakistani. The nationality of a man in the intensive care remained unknown.
The two vehicles collided head-on in the desert area, Lieutenant Colonel Saeed al-Dawoudi said in the statement, adding that a car later crashed into the wreckage.