The terrorists exchanged fire with security forces for nearly 12 hours (AFP Photo)

The three terrorists who stormed a police station in Punjab's Gurdaspur this morning "seemed tall, athletic and well-trained," said a Special Weapons and Tactics (SWAT) commando of Punjab Police who was part of the counter-terror operation.The attackers - between 25 and 30 years of age, the SWAT commando said - hid on the second floor of an empty building in the police station complex and exchanged fire with security forces for 12 hours.The commando said one of the terrorists shifted his position constantly, leading them to believe for that there were more than three people holed up. "One person was shooting at us from different points giving the impression of many people being there. We finally realised there were only three and we managed to reach them," he said.The gun battle ended at about 5.30 pm with all three terrorists being shot dead. They wore Army fatigues which had no labels or tags that could identify them and had carried a small amount of food.The terrorists used grenades made in China, said sources, adding that three AK-47, at least 10 magazines and two navigation devices with GPS were also found.Very early on Monday morning, the terrorists fired at a public bus in Gurdaspur, near the Pakistan border, before car-jacking a Maruti 800, pulling up at the police station and opening fire with their automatic weapons.The terrorists killed four police officers and three civilians in today's attacks.This was the first major attack in Punjab in eight years. Government sources told NDTV that Pakistan's "ISI has been encouraging the revival of Khalistan militancy over the last year". About 50,000 people died in the militancy that swept through Punjab starting in 1983 as part of a violent demand for a separate Sikh homeland.