Stating that no individual has been detained yet, the Indian Army said on Wednesday evening that a search team has located the INSAS rifle along with the magazine used in the killing of four armymen inside the Bathinda military station in Punjab.

"Joint teams of the Army and police will now undertake forensic analysis of the weapon for ascertaining further details," the Army said in an evening bulletin.

Two unidentified persons in civil dress opened fire at army personnel sleeping in the barracks of the military station early on Wednesday morning, killing four armymen, said Superintendent of Police (Investigation), Ajay Gandhi, adding that 19 empty shells of an INSAS rifle were recovered from the spot.

The firing took place at about 4.35 a.m. on Wednesday at the military base -- the largest in Asia -- located some 100 km from the Pakistan border.

Gandhi, who is heading the police team probing the incident, refused to comment on the use of weapon/weapons in the crime.

"The matter is still under investigation," he told the media.

The officer said that 19 empty shells of an INSAS rifle were recovered from the spot, adding that the deceased -- Sagar, Kamlesh, Santosh and Yogesh -- were asleep when the assailants opened fire inside the military barrack.

The South Western Command headquarters said the balance number of rounds in the INSAS rifle would only be available after forensic analysis.

"The joint investigation with Punjab Police is in progress. All possible assistance is being provided. No individual has been detained or apprehended yet," it added.

Earlier in the day, the command headquarters had said in a statement that it has been "ascertained that in the unfortunate incident, four army jawans of an artillery unit succumbed to gunshot injuries sustained during the incident".

"No other injuries to personnel or loss/damage to property have been reported. The area continues to be sealed and a joint investigation with Punjab Police is being coordinated to establish the facts of the case," the statement said.

It added that all aspects, including the possible use of an INSAS rifle and 28 rounds of ammunition that went missing two days back, are being probed.

Senior Superintendent of Police (Bathinda), Gulneet Singh Khurana, told the media that "it was not a terror attack and seemed to be some internal development in the military station".

The Bathinda cantonment, which houses one of the biggest ammunition depots in the country, is located along National Highway-7 on the Chandigarh-Fazilka stretch that further leads to Rajasthan.