The security forces have launched "Operation all-out" against militants across the Kashmir Valley.
Itoo was one of the longest surviving militants and was considered as the Hizb's top commander in south Kashmir, police sources said.
On Saturday evening, Kashmir's inspector general of police, Muneer Khan told a local newspaper that several militants were surrounded by forces in Shopian, but another bunch was shooting at the security team from an open area outside the cordon. Over a dozen civilians were injured as the security forces fired live ammunition to quell the stone-pelting mobs. The other two militants killed in the gunfight are Umar Majeed of Kulgam and Irfan-ul-Haq of Shopian.
Jammu and Kashmir police chief S.P. Vaid tweeted on the success: "One of terrorists killed today morning at Shopian is identified as Yasin Itoo; operational commander of Hizbul Mujahideen". The operation against the terrorists continued for around 20 hours.
Itoo, also spelt as Yatoo, was a resident of Chadoora area of Badgam district. He said in the initial gunfight five soldiers, including an officer, sustained injuries and were shifted to Army 15 core hospital in Badamibagh Srinagar.
Since January the police and the army have killed four top militant commanders having vast operational capabilities. Two of them later succumbed to injuries.
The operation began after security forces received inputs that terrorists are present in Awneera village of Zainapora area of the district.
Meanwhile, the internet services have been reportedly snapped in district Budgam. At the time of withdrawal of the CASO party from the encounter site, the militants fired indiscriminately upon army vehicles in which one person namely Mohammad Syed of Shopian was injured. A cordon was laid to ensure Itoo has no escape plan.