The arrests were almost immediate as the police raided the BHU hostels and surrounding area and nabbed -- Rupesh, Abhishek Rai and two others.

Late on Tuesday these four bike-borne men had opened fire at Guarav Singh in front of the Lal Bahadur Shastri Hostel, Circle Officer, Varanasi Cantt Anil Kumar Singh told IANS.

Gaurav Singh, who sustained bullet injuries in his stomach, was rushed to the Trauma Centre of Institute of Medical Sciences at BHU, where he succumbed to his injuries on Wednesday.

"Prima facie it seems to be a case of personal enmity," Kumar said.

According to students, Singh was talking to his friends when the bike-borne assailants gunned him down at around 7 p.m.

The incident caused panic in the campus, and students created havoc in the Trauma Centre.

The slain student was pursuing Masters in Computer Application and was jailed in 2018 for his involvement in a fight in December 2017. He was expelled from the college later.