"We tried to leave yesterday after authorities relaxed the curfew for a few hours, but we couldn't as the main road leading out of Mingora was literally jammed with the flood of fleeing people."
The army has also accused the Taleban of holding the civilian population hostage and blocking their exit.
Mobile phone networks, water and electricity have all been cut in the town which is normally home to half a million people. There are fears that food and medicine will run out if the fighting does not end soon.
Our correspondent says the government is hoping for a quick victory, while it still has the support of the Pakistani people.
The US says the militants in northern Pakistan pose a direct threat to its security, and has demanded they be confronted.
Pakistani military spokesman Gen Athar Abbas said the military's objective was to eliminate the militants from the Swat valley and also the neighbouring districts of Dir and Buner.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.