According to police, those arrested are FSU President Ramchandra Yadav, secretary Jaya Prakash Yadav and Santosh Yadav.
Superintendent of Police Bhupal Bhandari said the three have been kept at District Police Office, Rajbiraj.
Meanwhile, FSU Vice-president Tarakeshwar Yadav denied having beaten the campus chief.
Students had closed the bazaar and transport services in Rajbiraj in the afternoon to protest against the campus chief’s beating and demanding action against those involved in the incident.
The bazaar and transport services have, however, resumed from Tuesday evening.
Campus chief Sah is undergoing treatment at Sagarmatha Zonal Hospital.
NCC, ASCOL, Surkhet Campus into semis