The incident happened in the Bada Telma area near Bhikhari Thakur Chowk, they said.

An altercation broke out between two groups, said to be supporters of the BJP and RJD, over allegations of irregularities during polling that happened on Monday in the area, amid which shots were fired.

One person was killed on the spot, and three others were injured, a police officer said.

The deceased was identified as Chandan Yadav (25), he added.

"The injured persons were admitted to the nearest hospital. Later, two of them were sent to Patna for better treatment," Superintendent of Police Gaurav Mangla said.

"A case has been registered and an investigation is underway. Three persons have been arrested in connection with today's incident," he said.

Internet was also suspended in the district to prevent a flare-up, he added.

RJD president Lalu Prasad's daughter Rohini Acharya was the Mahagathbandhan candidate in Saran against BJP MP Rajiv Pratap Rudy.