At least three BSF personnel sustained bullet injuries after gunmen fired at security forces in Manipur's Thoubal district, police said on Thursday.

The incident occurred late Wednesday night when the gunmen from a mob which "attempted to breach the Thoubal police headquarters" fired at the security personnel, a police statement said.

The mob, first, targeted the 3rd Indian Reserve Battalion at Khangabok in Thoubal district and security forces repelled them using minimum force.

"Further, the mob attempted to breach Thoubal police headquarters, prompting the security forces to use the force. Armed men from among the mob fired with live rounds. As a result, three personnel from BSF sustained bullet injuries," the police statement said.

The three, identified as constable Gourav Kumar, ASI Sobram Singh and ASI Ramji, have been sent to a private hospital.

The district administration imposed a curfew in Thoubal.

However, people belonging to essential services including health, media, and those involved in the functioning of courts and those going to airports, are exempted from the purview of the curfew.

The fresh violence in Thoubal was reported after two Manipur Police commandos were killed and two sustained bullet wounds as heavily-armed militants targeted them in Moreh, a business town close to the Myanmar border, on Wednesday, officials said.