In the worst attack on the Army in many years, heavily armed militants suspected to be from Pakistan-based JeM stormed an army base in Uri in Kashmir killing 17 jawans early today, prompting Prime Minister Narendra Modi to assert that those responsible "will not go "unpunished.

Located barely a few kilometres from the Line of Control (LoC) and some 70 km from Srinagar, the base was subjected to the brazen attack by four terrorists at around 5.30 AM, causing heavy casualties in the Dogra regiment which lost 17 of its men. 20 more army personnel were injured, some critically, and were airlifted to the army base hospital in Srinagar.

After the three-hour gunbattle, four terrorists were killed and army was combing to ensure there were no other militants. Most of the army casualties resulted from the fire in tents in which jawans were sleeping.

India reacted strongly to the deadliest attack on the Army in Jammu and Kashmir in a quarter-century-old insurgency that sparked an outrage with Modi strongly condemning it. "We strongly condemn the cowardly terror attack in Uri. I assure the nation that those behind this despicable attack will not go unpunished," Modi tweeted.

Union Home Minister Rajnath Singh pointed a finger directly at Pakistan, saying it is a "terrorist state" and should be isolated while BJP leader Ram Madhav said days of strategic restraint are over and suggested that "for one tooth, the complete jaw" should be the policy after the attack.

Soon after the news of the attack broke, Army Chief Gen Dalbir Singh Suhag rushed to Uri followed soon by Defence Minister Manohar Parrikar, who cut short his Goa visit. Parrikar was briefed at Army's headqqarters in Srinagar.

Leaders across the political spectrum including Congress President Sonia Gandhi condemned the attack. President Pranab Mukherjee said India will not be cowed down by such attacks and that it will thwart the evil designs of terrorists and their backers.

The attack at the administrative base of the 10 Dogra, which top Army officials described as a "serious setback", was launched at 0530 hours and ended at 0830 hours with the killing of four terrorists and martyrdom of 17 soldiers.

Explosions and gunfire erupted as the militants attacked the camp, which is located barely few metres away from the Army's Brigade Headquarters in Uri town. The jawans of the Dogra Regiment were sleeping in a tent which caught fire due the explosion. The fire also engulfed the nearby barracks, official sources said.

DGMO Lt Gen Ranbir Singh called up his counterpart in Pakistan expressing "serious concerns" over Pakistani marking found on the equipment used by four "foreign" terrorists.

"All four killed were foreign terrorists and had carried with them items which had Pakistani markings. Initial reports indicate that the slain terrorists belong  to Jaish-E-Mohammed tanzeem," Lt Gen Singh said in a brief statement to the media at South Block in Delhi.

He added that since "some the terrorists had some items with Pakistani markings, I have spoken to Pakistan DGMO and conveyed our serious concern on the same".

He said that the terrorists had fired incendiary ammunition along with automatic fire of small arms that led to army tents and temporary shelters catching fire. "There have been a total of 17 Army fatal casualties. Of these, 13-14 casualties have been due to these tents/shelters having caught fire," he said.