After a fierce gunfight of nearly 15 hours, security forces killed all five terrorists, suspected to be from Pakistan, who breached security and entered a frontline Indian Air Force (IAF) base near Punjab's Pathankot town on Saturday, officials said.Police sources said that at least three IAF security personnel were killed and four others were injured in the terror attack that started around 3.30 a.m. The counter offensive lasted nearly 15 hours."I congratulate our armed forces and other security forces on successfully neutralising all the five terrorists in 'Pathankot Operation'," union Home Minister Rajnath Singh tweeted on Saturday evening."We have also lost security personnel in Pathankot attack. My heartfelt condolences to their families. We can never forget their sacrifice," he said.Though the firing stopped around 9 a.m. after the four terrorists were neutralised, sounds of firing and grenade explosions were heard again around 11.30 a.m. The counter offensive ended after nearly 15 hours as a lone terrorist engaged the security agencies in a gun battle inside the base, located around 250 km Chandigarh.