Jammu, May 30 :    Jammu, May 30:  Shells streaked across long stretches of the International Border and the Line of Control in the dark and a huge column of smoke spiralled up when dawn broke, capping a night that saw one of the heaviest exchanges of fire since the border build-up began. Late on Wednesday night, Indian troops in the Samba sector rolled out heavy artillery guns to respond to the heavy Pakistani shelling. Indian Army sources said the retaliatory strike destroyed the headquarters of the North Light Infantry Battalion at Tarapur across the border. The sources pointed to the towering pillar of smoke as evidence of the destruction and put the number of casualties on the Pakistani side at more than 100. 'Unlike the Pakistanis who are targeting civilians, we are shelling military areas. Radio intercepts from across the border reveal that casualties have been high. But Pakistan, known to hide their casualties, has still not made public the number of their men killed,' an army source said. 'The heavy shelling resorted to by the Pakistan Army all along the IB and the LoC in Jammu and Kashmir since the last two days has been met with a devastating reply from our side,' a senior officer said. The army feels that the continued heavy shelling by Pakistan is aimed at pushing in militants. 'We know their gameplan and have begun targeting military installations all along the border. But infiltration is still continuing with Poonch Akhnoor and Rajouri areas becoming the main routes,' the officer added. Official sources said there were as many as 32 routes in the state that are used by the terrorists to sneak in under the cover of firing and shelling. The army and police have drawn up a plan to check infiltration after intelligence reports warned that over 100 extremists were waiting across the Samba frontier to sneak into India. 'The rise in firing and shelling in the area points to the fact that Pakistan is now looking for new routes to push in terrorists. Our intelligence inputs categorically state that as the days pass and before the monsoon sets in, Pakistan will try to step up shelling in Samba. We are keeping a close watch on the sector, considering its proximity to the national highway to Pathankot. All streams are also being closely monitored as the militants often use them,' a senior police officer said. He conceded that infiltration cannot be completely checked as vast tracts on the border and the LoC are inhospitable and do not have army or police presence. But orders have now been issued to shoot those who fail to identify themselves. 'Things have become different after Kaluchak (where over 30 people were killed when an army camp was attacked). Even Indian villagers straying too close to the IB or the LoC can be shot. We have warned civilians who return from their camps to tend to their fields and cattle that times are dangerous,' an official said. Troops build-up across the IB and the LoC is continuing unabated. 'While we do not want war, we want to teach Pakistan a lesson. The shelling of the Northern Light Infantry Battalion headquarters at Samba is the first of a series of such tactical strikes.We want to push the Pakistan army further from the border,' an officer said.