Imphal, Dec 2 : Two day after the Rs 18.85 crore bank robbery, no breakthrough was achieved even as the security forces continued their massive operations on Saturday to nab the armed gang which looted the cash from a Punjab National Bank (PNB) branch in Manipur's Ukhrul town. A senior police official on Saturday said that Inspector General and Deputy Inspector General rank Police officers have been entrusted with the task to arrest the robbers who have looted the money at gunpoint on Thursday. Unidentified masked armed gang of ten persons looted Rs 18.85 crore from PNB Ukhrul branch when the bank employees were counting the amount after the day's transaction. Immediately after the incident, the senior Manipur Police officers rushed to the hill district and are stationed there till now supervising the search operations. The investigation officer summoned the bank officials and the Manipur Rifles personnel, who guard the bank branch, for their statement. Meanwhile, Manipur Chief Minister N. Biren Singh strongly condemned the incident and assured that the robbers would be nabbed at the earliest. Police, quoting eyewitnesses, said that 10 heavily-armed unidentified masked men reportedly carrying sophisticated weapons stormed into the PNB bank branch situated in Viewland-I in Ukhrul town just before the evening and looted Rs 18.85 crore. "The security personnel and bank staff were tied with ropes at gunpoint and locked inside the store and washrooms by the armed men who fled with the cash," a police official told IANS. This is the first time such a daring incident has happened in Ukhrul town since the ethnic violence broke out in Manipur seven months ago. A sum of Rs one crore was looted by the armed gang from an Axis Bank branch at Manipur's Churachandpur in July. /IANS