Binoy Das, the headmaster on Memari Boro-Palashon High School was travelling by bus from Kalna to Burdwan this afternoon.
The student of Harishabha Hindu Girls' High School and a resident of Mithapukur area of Burdwan was also on the same bus along with her mother, said Priyobrata Bakshi, Inspector in-charge of Burdwan police station.
The victim was seated next to Das and when she dozed off, the headmaster allegedly molested her, Bakshi said adding, the girl woke up and raised an alarm prompting other passengers of the bus to beat up Das and hand him over to the police.