The incident took place at Katiapur village in Jaswantnagar, Etawah district.
Jaswantnagar is an SP stronghold and has been held by the ruling party in the last several decades.
It was first represented by SP supremo Mulayam Singh Yadav in the Vidhan Sabha for seven successive terms and has been thereafter represented by Shivpal Singh Yadav.
Shivpal is engaged in a bitter power struggle with nephew and Chief Minister Akhilesh Yadav.
When asked by the media in Saifai to comment on the stone-pelting incident, Akhilesh Yadav refused to comment, saying "I am not aware of the incident".