Miscreants allegedly pelted stones at the Shatabdi Express travelling from Kanpur to Delhi on Thursday evening while RSS chief Mohan Bhagwat was on board, police said.
The incident occurred near Firozabad and has prompted an investigation by railway and local police authorities. Officials said no injuries were reported, though a coach window was damaged in the attack.
According to police, the outer glass pane of a window in coach E1 was shattered after a stone struck the train.
Mohan Bhagwat and Uttar Pradesh Panchayati Raj Minister Bhupendra Chaudhary were travelling in the same coach at the time of the incident. Police said a stone landed near the window beside their seats.
Railway officials, police personnel and district administration officers rushed to the spot after receiving information about the incident.
Officials said the stone pelting damaged only the outer window pane and did not cause any injuries to passengers.
Police on Friday said CCTV footage from the area is being examined to identify those involved. Efforts are underway to trace and arrest the accused.
Railway Protection Force personnel and district police teams conducted searches through the night following the incident. A case has been registered at Rasulpur police station.