The terrorists sneaked into the base, about 100 km from Srinagar, around 5:30 am, threw several grenades and fired indiscriminately, causing the most deaths the army has suffered in a single attack in years.

Most of the soldiers were burnt alive when their tents caught fire because of the grenades. The attack took place during a change of command, which means one unit was replacing another and soldiers were in temporary shelters.

Sources said the camp could be observed from the hill tops across the border and it is likely that the terrorists were aware that the regiments were turning over.

The Director General of Military Operations, Lieutenant General Ranbir Singh, said the terrorists were foreigners and there are clear signs of the role of the terror group Jaish-e-Mohammed, whose chief Masood Azhar is based in Pakistan. The group had been involved in the attack on Pathankot air base in January during which 7 army-men were killed.

The terrorists had "items of Pakistani markings", said Lt General Singh, adding that he had conveyed "serious concerns" to his Pakistani counterpart. Besides four AK 47 rifles and grenade launchers, a large number of grenades and food with Pakistani markings have been found in search ops.

Around 30 soldiers were injured in a three-hour gunbattle with the terrorists who are believed to have crossed a canal along the Line of Control, cut through the fencing and infiltrated into Kashmir.

"Pakistan is a terrorist state and it should be identified and isolated as such," Home Minister Rajnath Singh said in tweets, adding that the attackers were "highly trained, heavily armed and specially equipped".

Defence Minister Manohar Parrikar, who visited Kashmir with Army Chief Dalbir Singh, tweeted, "The supreme sacrifice of 17 brave Soldiers will not go in vain. My salute to them. Reviewed situation in Kashmir following Uri attack with Army Chief & Commanders. Instructed to take firm action against those responsible".

Jammu and Kashmir Chief Minister Mehbooba Mufti said in a statement that the attack appeared to be aimed at creating a "war-like situation" in the region.