Later, his car route was diverted for security reasons.
The authorities have cordoned off the area and have initiated a probe to find out the person behind the same.
Mulayam is contesting the Lok Sabha elections from Mainpuri seat. He reached Etawah later Sunday evening long with son and party chief Akhilesh Yadav and Kannauj MP Dimple Yadav.
The nomination filing ceremony will however be missed by his brother Shivpal Yadav, who is the founder of Pragatisheel Samajwadi Party who said that he will miss the event as political adversaries would be there.
"My adversaries would be there. Hence I cannot go there," said Yadav.
Seven-phase Lok Sabha polls are set to begin in Uttar Pradesh on April 11 and will go on till May 19. The counting of votes will take place on May 23. In Uttar Pradesh, where 80 seats are at stake, polling will be held during all seven phases.