Meanwhile, a heavy contigent of army, SOG, CRPF and police have launched a hunt to nab the assailants.
Besides 24-year-old Mattoo alias "Jana", the other two bodies were those of 18-year-old Adil Mushtaq Mir alias "Nana" and 20-year-old Nisar Ahmad Wani.
"Junaid was also involved in the killing of an assistant sub-inspector and a constable near a bus stand in Anantnag previous year", he said.
Another teenage boy was killed in clashes near the encounter site in Arwani village after he was hit by a bullet in the chest. Extremist group Lashkar-e-Taiba has claimed responsibility for the attack, Hindustan Times reported.
Among the slain policemen was Feroz Dar, a Station House Officer (SHO), the sources said.
In Occupied Kashmir, two civilians were martyred and several others injured due to the use of brute force by Indian troops on unarmed civilians across the territory since last evening.
Earlier on May 28, militants attacked a police party at Phambai area of Kulgam in South Kashmir, killing five policemen and two bank guards.
Kashmiri leaders who challenge India's sovereignty over Kashmir called for a general strike on Saturday (today) to protest the killing of the civilians. The cop was rushed to a local hospital but he did not survive.
"When the encounter was on an unruly mob instigated by the militants started pelting stones with an intention to disturb the operation and give chance to holed up militants to escape". Sources said the Army was checking vehicles in the area and the auto did not stop for checking.
Both the injured were shifted to District Hospital Bandipora for treatment where from they were shifted to SKIMS Soura for specialised treatment.
Authorities on Friday again blocked high speed mobile Internet facility in the area fearing escalation in tempers over civilian killings.