People familiar with the matter told NDTV that the four soldiers died after a Pakistani mortar shell struck near the entrance to a bunker, which could not absorb the intensity of the blast.
The bodies of Captain Kapil Kundu, 22, Rifleman Ramavatar, 28, Rifleman Subham Singh, 22 and Havilder Roshan Lal, 42, will be sent to their hometowns after a tribute in Jammu.
"We will not forgive Pakistan's actions. It will prove to be Pakistan's foolishness and will cost them dearly," Hansraj Ahir, Minister of State Home Affairs said.
Pakistan intensified firing at Indian military posts and villages along the Line of Control or LoC in Poonch and Rajouri districts on Sunday morning. A teenage girl and a soldier were also injured in Poonch.
"Indian Army retaliated strongly and effectively and heavy damage has been inflicted on Pakistani Army posts," said a defence statement.
"Pakistan Army along the border has been supporting infiltration by terrorists," said Vice Chief of Army Staff Lieutenant General Sarath Chand.
The shelling has stopped for now and the forces are keeping a close watch. Over 80 schools in the district are closed and people have been told to stay indoors.
The Army said that Pakistan troops fired five or six anti-tank guided missiles indiscriminately in the area. The incident took place at an altitude of 3,000 feet in a densely forested part of the LoC in Bhimber Galli in the Rajouri district.
It was the second time in three days that the Pakistani Army targeted Poonch. They had attacked military and civilian facilities in nearly a dozen areas of the Balakote sector last week.