Deputy Superintendent of Police (DSP) Kumar Ekle said the clash took place when the police standing guard prevented the locals from forcibly entering the venue of the convocation of Lalit Narayan Mishra University. Angry at being stopped, the people threw stones at the police injuring some of them.
This prompted the police to lathicharge the mob and burst teargas shells to disperse them, he said.
The crowd also threw stones at the vehicles of the district civil and police officials and smashed their window panes, Ekle said.
It was not immediately known whether anyone was injured in the police action.
The convocation function, which was also attended by Chief Minister Nitish Kumar, was unaffected by the clash and the dignitaries left for Patna later, he added.