RIO DE JANEIRO, May 17 (Xinhua) -- At least 11 people were killed and dozens were injured after a head-on collision between a bus and a van in Brazil's central-west state of Mato Grosso, bordering Paraguay and Bolivia, the Federal Highway Police said Tuesday.

       Initial investigations showed the two vehicles collided in the town of Sorriso, in the north of Mato Grosso, because the bus driver fell asleep at the wheel, the agency told local press.

       As many as 45 people were traveling on the bus bound for Sinop, some 500 kilometers away.

       The bus driver was in serious condition, while the van driver suffered only minor injuries.