India tightened security on its border with Pakistan on Monday after attackers stormed on a police station in Punjab’s Gurdaspur district, killing at least seven people and injuring several others.A group of three to four attackers came in a white Maruti car after hijacking it from the Old Pathankot-Gurdaspur road and opened fire at the police station around 5.30am.The Indian army has launched an operation against the “militants” who are holed up in a police station complex in Gurdaspur district of the state and exchanging fire with security personnel, Indian media reports said.