Stones were hurled at the Lucknow-Delhi Shatabdi Express near Firozabad railway station on Thursday evening while RSS chief Mohan Bhagwat was on board, police said.
The incident took place around 7.45 pm near the Pemeshwar Gate bridge on the Etawah-Tundla section when an unidentified person allegedly targeted one of the coaches of the 12003 up Shatabdi Express.
According to sources, Bhagwat, who had boarded the E1 coach at Kanpur, was safe and unharmed.
Following an alert from Railway officials, senior police officers, including Firozabad SP Aditya Langhe, Agra Railway SP Anil Jha and SP (City) Ravi Shankar Prasad, rushed to the spot.
Police said the exact circumstances surrounding the incident, including the identity of the person who threw the stone, would be ascertained after examining CCTV footage from the area.
(With inputs from PTI)