Complex sentence: Clearing and mopping-up operations were carried out by troops under Colonel G. V. Ravipriya from 3:30 pm to 6:30 pm that evening, but they didn't encounter this last group of LTTE fighters that day.
Split into simpler sentences: Clearing and mopping-up operations were carried out by troops under Colonel G. V. Ravipriya from 3:30 pm to 6:30 pm that evening. But they did not encounter this last group of LTTE fighters that day.