An Indian trooper was seriously injured on Friday when Pakistan Rangers resorted to unprovoked firing on the International Border in Hiranagar sector in Jammu and Kashmir, an official said.The firing was the latest in a series of ceasefire violations by Pakistan since the September 29 surgical strikes by the Indian Army on terror launch pads in Pakistan-administered Kashmir, officials said."The (Friday) ceasefire violation by Pakistan occurred at around 9.30 in the morning (in Kathua district). It was effectively retaliated by us. Some casualties have been effected on the other side," an officer of the Border Security Force (BSF) told IANS."A BSF soldier suffered a bullet injury. He has been evacuated to the Government Medical College, Jammu. His condition is critical," the officer said.The ceasefire violation comes a day after BSF troopers on Thursday foiled a major infiltration bid on the International Border.