The attack came a week after Indian Prime Minister Narendra Modi made an impromptu visit to Pakistani counterpart Nawaz Sharif, in a bid to revive bilateral talks between the nuclear-armed neighbors that had previously been derailed by militant attacks.
Officials said the gunmen, wearing army fatigues, managed to enter the Pathankot airbase. Once inside, they opened fire indiscriminately. They had earlier hijacked a police officer's car and driven it to the heavily guarded base - tactics used in earlier attacks believed to have been perpetrated by Pakistani-trained militants, Punjab's police chief Suresh Arora told Reuters.
VIDEO, 4 Militants, 3 Guards killed in Major Attack to Indian Airbase in Border of Pakistan
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Sporadic gunfire and helicopters flying overhead could still be heard as an operation to comb the base in search of any more gunmen continued, police said.
Although there was no immediate claim of responsibility for the attack, But Indian security sources said that, based on their initial analysis, the attack may have been carried out by "Jaish-e-Mohammed", or the "Army of Mohammed", a militant group based in Pakistan that demands independence for Indian-ruled Kashmir.
The raid resembled an assault last July by gunmen in uniform on a police post in a Punjabi border town that killed nine people.
However, Saturday's pre-dawn attack was much more audacious in targeting a large military facility, from which India's Russian-made fleet of MiG-21 fighter jets and Mi-35 attack helicopters fly.
The state of Punjab and neighboring Jammu were on high alert and all defense bases had been sealed.
Pathankot air base
The new strategy of the terrorists is to identify defense bases near the border and launch attacks," said the home ministry official.
Pathankot air base
Security experts say that tight security along the disputed frontier running through Kashmir has pushed the focus of militant activity further south towards softer targets in India's Punjab state.
India and Pakistan have fought two wars over Kashmir since independence and partition in 1947.