According to SP (Shamli) Vijay Bhushan, the four youths have been identified as Mohit, Amit, Shani and Gaurav, all residents of Bhaju village.
The cleric, Noor Mohammed, was allegedly assaulted by the four accused as he was travelling on a bus from Shamli to Shahpur near Bhaju village.
A case has been registered in this connection, police said.