A dispute broke out between two communities in Harinagar Rural Municipality of Sunsari.
The dispute had occurred after a fight between two youths on Thursday.
Following the incident, the District Administration Office clamped an indefinite curfew in Harinagar Rural Municipality and Dewangunj Rural Municipality of Sunsari.
After the people from different communities attacked each other during the curfew, police opened fire to take the mob under control.
Two persons were injured in the police firing. They are receiving treatment at the Nobel Medical College.
The dispute had ensued on Thursday after a group of people attacked Jeevan Mehta.
Injured Mehta is undergoing treatment at the Dharan-based BP Koirala Institute of Health Sciences.
SP Bipin Regmi of the District Police Office, Sunsari said that police fired dozens of bullets into the air to take the mob under control after more than 5, 000 people boycotted the curfew and attacked each other.
He said that action will be taken against those who go against the law.