Islamabad:
Gun and mortar fire sounded, as Pakistani Army moved in troops to wrest control of the Swat valley from the Taliban, and fears of an impending battle triggered a major exodus with thousands of men, women and children fleeing.
Army helicopters gunships attacked Taliban positions in an around Mingora, the main town as the militants seized government buildings and laid mines on the towns main approaches.
The impending hostilities signalled the collapse of three month old truce between the extremists Taliban and the provincial government. Fearing a major operation, the first wave of exodus began which the authorities said could reach a staggering 500,000.
Military spokesman Maj Gen Athar Abbas refused to say whether the gunfire heralded the start of the major operations merely saying, "all contingencies have been worked out".
As clashes rocked the entire Swat valley, the expansion of the Pakistan Army's operation will test its ability to counter a guerrilla warfare as also resolve of the civilian leadership to fight the Taliban, who till recently were its partners in peace.
Three militants were killed and a policeman was injured in fresh clashes.