A BSF patrol party noticed some movement of militants at two posts - S M Pur and S M Pur-one - in Ramgarh subsector of Samba and challenged the militants, police officials said.
Pakistani troops then opened fire and the BSF retaliated and the exchange between the two sides continued intermittently for half-an-hour.The militants later fled.
Inspector General of BSF, Jammu frontier, A K Sarolia said a red alert has been sounded in the entire border line with Pakistan and patrolling intensified.
The militants, he said, did not succeed in infiltrating into Jammu and Kashmir.
Pakistani troops had also opened fire at around 2240 hrs last night at Kandral border outpost along the international border, drawing retaliation from BSF personnel.
In a pre-dawn attack on Sunday, border outposts at Londi and Bobiya were targeted and at a flag meeting held. India had lodged its protest against ceasefire violation.
On Saturday, a BSF jawan was killed and two others were injured in cross border firing at Kranti post near LOC in Poonch.
There have been 28 incidents of such ceasefire violations till November 25 by Pakistan along the Line of Control.
During the last four years there have been 129 incidents of ground ceasefire and 43 air space violations by Pakistan.