The three teenaged girls were killed on the spot when the MSRTC bus, going from Kati to Malkapur, collided with the truck coming from the opposite direction, they said.
The students were on their way to Chandak Vidyalaya in Malkapur and used to regularly take a bus to go to school.
Police said 14 other bus passengers injured in the mishap were rushed to Malkapur and Buldhana civil hospitals.
The drivers of the bus and truck escaped unhurt.