The Indian Army was giving a befitting reply and heavy exchanges were on, they added.
Pakistani forces opened unprovoked heavy firing and shelling along the LoC in Bhimbher Gali sector of Rajouri district this evening, senior Army officials told PTI.
In the shelling, three jawans were killed, they said. An officer, who was injured in the shelling, also succumbed to his injuries, they added.
Six days before his birthday, 22-year-old Captain Kapil Kundu, a resident of village Ransika in Haryana's Gurgaon district, was killed in the shelling, Army officials said.
Forty two-year-old Havildar Roshan Lal, resident of Samba district, 27-year-old Riflemen Ramavatar of Gwalior in Madhya Pradesh and Subham Singh (23) of J&K's Kathua district were also killed, he said.
"Martyrdom of Indian Army soldiers will not go in vain.
The unprovoked action by the Pakistan Army will be given a befitting response," an official said.
Earlier in the day, two teenagers and a jawan were injured in Shahpur sector of Poonch district in shelling from across the border, a police official said.
He identified the injured civilians as Shahnaz Bano (15) and Yasin Arif (14), residents of Islamabad village.
A defence spokesman said the Pakistan Army initiated unprovoked and indiscriminate firing of small arms, automatic weapons and mortars around 1110 hours. The Indian Army retaliated strongly and effectively, he said.
In another ceasefire violation by Pakistan in Rajouri district, a police official said six mortars exploded near Neaka Panjgrain and Tarkundi villages in Manjakote sector around 1540 hours.
The mortars were fired by Pakistani troops and the Indian forces guarding the LoC responded, triggering an exchange of fire between the two sides, he said.
Chief Minister Mehbooba Mufti expressed pain at the deaths due to Pakistani shelling along the LoC. "My condolences to the families of the deceased," she said.
Authorities in Poonch issued an advisory asking people to stay inside their homes.
"All 84 schools located in 0-5 km from the LoC stretch from Sunderbani to Manjakote shall remain closed for the next three days," Deputy Commissioner, Rajouri, Shahid Iqbal said.
Officials said the situation was very tense as firing and shelling by Pakistani troops continued round-the-clock.
In January alone eight civilians and six security personnel were killed and around 70 injured in ceasefire violations by Pakistan troops along Indo-Pak border in Jammu region.
Pakistani troops carried out intense shelling along the IB in Jammu, Kathua and Samba districts and LoC in Poonch and Rajouri districts from January 18 to 22.
While there were no ceasefire violations by Pakistan reported along the IB since January 22, intermittent shelling has taken place along the LoC.