The six killed included two army soldiers and four militants while the injured include a major and three other ranks, police said.
"Bodies of four militants belonging to Lashkar-e-Taiba (LeT) outfit were recovered in Marsari village of Kupwara district on Wednesday," a senior police official told IANS.
Security forces were looking for the bodies of several more guerrillas, who were believed to be killed, in the debris of the house that was destroyed in the gunfight that began Friday evening, the official said.
Troops of counter insurgency Rashtriya Rifles (RR), special operations group (SOG) of state police and paramilitary Central Reserve Police Force (CRPF) had surrounded an abandoned house in Marsari village on Friday following information that a group of guerrillas was hiding inside.
When the security forces moved close to the house the militants opened fire on them, the police said.
In the gunfight the house which the guerrillas used as a fortified bunker was destroyed.