Imphal, Aug 29 : Two persons, including a village defence volunteer (VDV), were killed while seven others were injured in heavy firing between two rival groups at Narainsena in Bishnupur district on Tuesday, the police said. The police said while the VDV was killed after a bomb suddenly exploded due to his mishandling, another person succumbed to his bullet injuries later. Seven wounded persons were shifted to the government hospital where their condition is stated to be stable. The police said that in a separate developments, four militants belonging to different outfits were arrested in different operations in Imphal East and Bishnupur districts and some arms and ammunition were seized from their possession. Two of the arrested militants belonged to the NSCN-IM and the People's Liberation Army (PLA), while two were overground workers of Kangleipak Communist Party (KCP). Seven looted firearms, 25 different types of ammunition and nine powerful bombs were also recovered during the operations from Bishnupur and Thoubal districts in the past 24 hours. The search operations were conducted by the security forces in the fringe and vulnerable areas of the five valley districts. /IANS